I usually would set the gear to one level and leave it at that if I felt comfortable -- however, I just heard of someone changing gears on stops and whatnot to help with the initial inertia from full rest and such.
I never have done this, as I just forced myself to deal with said level in both full stops and top speeds.
Is there anything bad about this, maybe having to do with the chain? Because I have a history of chain problems on every bike I've had (all cheap-ish, but some better than others). Is gear-shifting more good or bad or makes not much of a difference? I don't really shift ever as riding. Can this affect things more with the chain, both down to the tires and/or the mid-drive area itself of the bike?
Common issues I have are: chain breaking; getting stuck; shifting but not falling to the right links/gears.