The boiling time is about 60 minutes for a 5-gallon batch or 12 minutes/gallon.
I am interest to make so small beer batch. Should I adjust the boiling time per volume? To say, if my batch size is 0.5 gallons, should I boil for 6 minutes?
i would say no keep at 60 mins to get the most out of your hops and protien breaks. Just make sure you use a smaller / narrow pot to restrict the boil off.
keep it 60 mins you can go as low as 30 mins no lower