Well, those tubes are meant for jobs MUCH larger than a yoyo. The smallest jobs are meant to do at least a couple of bathtubs work of seal.
I’d say if you were doing a hundred yoyos, yeah, it would make sense and get used up. Do your throws, do your friends’ throws, do your family’s throws, invite the entire yoyo club over and do theirs. Just use it up, charge them a dollar or something. 4 yoyos and you recovered your cost. If you’re not in it for the money, that’s OK. Just don’t waste the stuff.
Personally, I’m just gonna stock up on the replacement rings and not worry about it. Yeah, it may cost more up front, but in the long run, I don’t have to buy a $4 tube of silicone that is gonna probably cure before I get back to it again. Then after a couple of rounds of this, which becomes more cost effective?
I’m all for DIY, but I also have to keep in mind costs to DIY vs costs of buying what I need instead.