Tedious to the nth degree. Train. Train. Train. Feed. Train. Poop. Feed. Train. Train. Rest. Sleep. Train. On and on, any mistakes and you're stuck with a bad digimon. You do this to get to the sliver of time where you can actually make progression with your digimon strong enough before it dies and redo it all.

Its a shame because the open world and collecting all the digimon is fun and fresh for the platform, but it really is just bogged down by an overblown tamagotchi system.