For a slow player to play faster, play within the 5 min-15 min each, range.
Don't know about deeper moves, but I'd say 45 min each+, (don't play here, go OTB). Or go Tactics Trainer.
Playing 10 minutes blitz here helped my chess play ALOT, and because a game takes around 20 minutes, I usually limit myself to 1 game a day and analyse it afterwards.
What time control is better for a slow player to learn to play faster
What time control is better to learn how to play better moves(think deeper 3-4 moves ahead)
Is there a time control that is sufficent to allow you to both think through better moves while also helping you to deal with playing slowly and running into time pressure.
What way should a player who plays slowly split up his games between different time controlss