Promoting
 

Will it affect your team's minor league to continually promote a player? I am currently at a passable minors, and I would like to promote players, but not if it will set me back to inadequate or slow down the further development of the system.

no the only thing that will cause your YS to drop a level, is to cut funding to it.

You should promote a youth every week, regardless of the level of
your YS.