I try to always make sure stems, tubes, repivots etc. are a good mechanical fit. But I will often use a bit of appropriate Loctite as a belt and suspenders. Especially for tubes that should be press fit, but sometimes the hole has a terrible surface finish or the fit is iffy, loctite helps make sure its waterproof and not going to work out. And it can be hard to judge the fit- it might seem like it will be a good fit, but is a little loose, but the stainless on stainless wants to gall when removing...- and the Loctite actually eases the assembly a bit even if it's actually a tight fit!