How many hours of daily piano practice is safe? safe in terms of hearing, musculoskeletal health and other? professionals practice for more than 3 hours daily. is that safe in the long run? also, how much daily guitar practice limits should i have?

I have known musicians who played those instruments for hours most days for many years without any health issues in old age. Practice,practice,practice!!! when you love playing music. Back off if you note overuse discomfort. When you love to play, you get 6 years of value in 6 months of practice. When you don't love playing you get only 6 months of value after playing for 6 years.