Weird Fusion Rules

[ShadowDude112]

So, when we're first introduced to Gotenks, they mess up 2 times and are successful the third time. They always refused after one ended. But when Gotenks is fighting Buu, he yells down into the crater he made that he'll have to wait another hour until he can fuse again. It's such a weird rule that comes out of nowhere. Why was it introduced?

[Hugo Boss]

Maybe this is the time the fusees need to recover their stamina after Fusion wear off. It's supposed to be a technique that tires them too much.

[Chuquita]

Maybe it's like "after you eat, wait an hour before swimming"? Maybe the fusion wouldn't last as long, or maybe they wouldn't split back up properly? (Like they split back and have each other's hair color or some of the personality traits don't go back to the correct person?)

[Sandubadear]

We don't know for certain that they tried again to fuse right away, maybe they had waited the hour "off-screen".

[Darkprince410]

So, when we're first introduced to Gotenks, they mess up 2 times and are successful the third time. They always refused after one ended. But when Gotenks is fighting Buu, he yells down into the crater he made that he'll have to wait another hour until he can fuse again. It's such a weird rule that comes out of nowhere. Why was it introduced?

Just because there's no time shown to have passed between the fusions doesn't mean that there wasn't time that passed. Goku, right when he first described the Fusion Dance to the boys, states that once the thirty minutes are up, they'll return to normal and won't be able to fuse again for awhile. It wasn't a random rule that was added later, but rather something that was shown before Gotenks even made his first appearance.

[TheGreatness25]

I'm sure that they did wait an hour between fusion originally, but of course nobody is going to show that. But either way, that's what's weird with fusion? Not the whole concept?

[Herms]

So, when Goku first explains about how Fusion only lasts 30 minutes, he notes that after it wears off they won't be able to fuse again "for a while". So there's precedent for the idea, but "a while" doesn't automatically make one assume a whole hour. And, as already noted, when Goten and Trunks practice Fusion, despite Goku's earlier comment, they do indeed seem to just try Fusion again as soon as they split back up. Piccolo even says after skinny Gotenks is formed that they'll try again "in 30 minutes", which seems to rule out them needing to wait extra time beyond the actual length of the Fusion.

When Piccolo contacts Goten and Trunks inside the Room of Spirit and Time to tell them Boo is on the way, Goten panics because they just finished fusing, but Piccolo reassures him that in their time Boo won't arrive for quite a while. In this case though, it seems like Goten is more worried about them being tired and worn out from being a Super Saiyan 3, rather than about a hard and fast rule for how long they have to wait between fusing.

So, as far as I can tell the "1 hour" rule indeed isn't mentioned at all until Gotenks randomly says it to Boo. Although he technically says that it'll be an hour before he can become "this strong again", which possibly means Super Saiyan 3 rather than Fusion itself. And when Gotenks-Boo explains his plain to Gohan, he mentions how he needed to wait an hour before the kids could become "Super Gotenks" again, and "Super Gotenks" is the name used specifically for Super Saiyan 3 Gotenks (in chapter 494's title, for instance).

Overall, it looks like waiting 1 hour may only be necessary for Super Saiyan 3 and/or using SS3 while fused. We know going SS3 further reduces the already limited time Gotenks can remained fused, so maybe it also lengthens the period between fusions? So in normal circumstances, the period between fusions would be a while (per Goku's original comment), but not long enough to bother showing or mentioning. There, that seems reasonable.

[Hitiro]

So, when Goku first explains about how Fusion only lasts 30 minutes, he notes that after it wears off they won't be able to fuse again "for a while". So there's precedent for the idea, but "a while" doesn't automatically make one assume a whole hour. And, as already noted, when Goten and Trunks practice Fusion, despite Goku's earlier comment, they do indeed seem to just try Fusion again as soon as they split back up. Piccolo even says after skinny Gotenks is formed that they'll try again "in 30 minutes", which seems to rule out them needing to wait extra time beyond the actual length of the Fusion.

When Piccolo contacts Goten and Trunks inside the Room of Spirit and Time to tell them Boo is on the way, Goten panics because they just finished fusing, but Piccolo reassures him that in their time Boo won't arrive for quite a while. In this case though, it seems like Goten is more worried about them being tired and worn out from being a Super Saiyan 3, rather than about a hard and fast rule for how long they have to wait between fusing.

So, as far as I can tell the "1 hour" rule indeed isn't mentioned at all until Gotenks randomly says it to Boo. Although he technically says that it'll be an hour before he can become "this strong again", which possibly means Super Saiyan 3 rather than Fusion itself. And when Gotenks-Boo explains his plain to Gohan, he mentions how he needed to wait an hour before the kids could become "Super Gotenks" again, and "Super Gotenks" is the name used specifically for Super Saiyan 3 Gotenks (in chapter 494's title, for instance).

Overall, it looks like waiting 1 hour may only be necessary for Super Saiyan 3 and/or using SS3 while fused. We know going SS3 further reduces the already limited time Gotenks can remained fused, so maybe it also lengthens the period between fusions? So in normal circumstances, the period between fusions would be a while (per Goku's original comment), but not long enough to bother showing or mentioning. There, that seems reasonable.

Or possibly that as a SSJ they would still have energy once the fusion is undone. What we see from the story is they lose their power to maintain the form before unfusing. So they would either not be able to maintain the SSJ3 fusion if they don't wait 1 hour instead of half an hour or the fusion time is drastically shortened because they still haven't fully recovered their power to maintain the fusion. Essentially something like this:

Goten
Ki: 5
Ki After SSJ Fusion: 4
Ki After SSJ Fusion: 0

Trunks
Ki: 5
Ki After SSJ Fusion: 4
Ki After SSJ3 Fusion: 0

SSJ3 Gotenks
Timelimit after 1 hour: 5 mins
Timelimit after 45 mins: 2.5 mins
Timelimit after 30 mins: 0 mins

After 30 mins they have some Ki returned but this may not be enough to actually obtain the transformation as transforming requires Ki itself. Then the further Ki consumption for maintaining the transformation.