I've been using those a lot for the first time in my current save, though that is having taken Barnsley from L1 to the Premier League. I rarely find many gems (hardly surprising at this level), but I've certainly got a decent amount of squad players and youth prospects over the seasons this way, so sell-on profits have been nice! Considering my budget has been woeful for both CH and PL, relying on being able to find at least a couple of free transfers per season to pad the team out has really helped.
But yeah, @erik45's imposed restrictions add an extra layer to things!