It’s the tricky question. How much practice is enough and what happens if I don’t practice enough?
The good news is that even without practicing much you will see results!! Just starting to change the way you think about your voice and understand how it works makes things start to shift and open up. I had a group of college students one year for 3 lessons and then they went on a 3-month summer break. None of them practiced and all of them came back astounded with the changes and freedom that was unlocking in their voice.
The reason!! When you start to learn the right way to use your voice things do start to change. When you learn you need less air for the high notes, not to squeeze in your throat when singing or singing gently is better than forcing your voice, things start to change.
Having said that you will progress faster, the more practice you do.
I have many professionals that come in for lessons that don’t have time to practice and they are all astounded with the progress in their voice.
So yes, it would be great to do a full effective 1-hour practice a day, but realistically most people can manage 5-10 minutes a day or a couple of times a week and see good results.