There is no such thing as a magic number. Daily practise even if it’s only 5 minutes is better than nothing. 30-60min/day wow! Terrific

a hour

No, 30 minutes to 1 hour is not enough if you want to improve your target language. I usually spend about 2 hours a day reviewing vocabulary and practicing the four language skills.

No ,you need more time if you want to learn quickly. You should listen Spanish music or podcast when you leave or workout,read books or news in Spanish while you check your social medias and learn the grammar too.Btw ,Everyday I practice it and nowaday I'm happy because I understand to English speaker

It depends on what you do with that time. If you talk to actual humans for an hour every day, then yes, you will improve.