agreed. the callouses and finger strenght take some time to develop.

when i first started playing guitar, my left hand fingers were soft and weak. over time, they adapted and now theyre like hunks of iron.

then i picked up bass as well, and when i stopped using a pick and started donig finger and slap style, my RIGHT hand fingers were soft and weak, but once again, they adapated and became hunks of iron.

you can probably supplement but not replace any real life learning with LDs