This is what Real Madrid is mostly doing and I think Barcelona are also huge in their young players chance to play with the main team in order to integrate them into the main team gradually. Bayern Munich is indeed having a very tight schedule this season and they need to have a enough squad that they can rotate with, so having those young players ready at anytime to participate with them is the best thing they should do now.
Chelsea have enough squad that they were able to have two main eleven players to start at every competition they’re participating in, that has given them more confidence in all competitions and also reduce fatigue in the players. Bayern Munich are on top of the league table now and can’t afford losing that position, so they need to do all they can in order to remain there and that’s by strengthening their squad more for the big challenge ahead of them.
You are absolutely right on the aspect of Chelsea having enough squad of two different eleven players to start every competition that they are participating. Thats what is called squad depth in football, and i like the fact that they have it now it paying off for them because i could remember during the beginning of the season when a clip of Chelsea training came out online, most fans from other clubs were laughing at them for having too many players.