question on auto

Since you can leave the light on for 24 hours a day, do they take a lot less time to grow say like half the time?

Yes and No.

They start flowing when they feel like it. So they take as much time as they want and you cant do anything about it. You can do the same thing growing reg seeds at 12/12 from the start.

ALSO, you NEED to give your plants some dark time or they never rest. Think of growing pot as a marathon. If you sprint(24/0) you'll make it until your tired. If you pace yourself(18/6) than you wont be tired until your done.

This is very much a strain related question the more
ruderalis the strain has, then the more auto it is...so yes the more light they have the more they grow the bigger they get most autos are done in 2 months thats about half the photo periodic's

Strain dependent for sure! But as said you can shorten a reg by starting at 12/12 but you would lose a lot. For an extra 20 days or more (its up to you). You would get more from a reg imo. Auto's are great for outdoor grows where an early harvest is desirable IMO. Not sure if i would pick an auto for an indoor garden over a reg.

Autos grow on a time schedule not light, but they do require light for a more bountiful harvest. In my limited experience, I found that 20/4 seemed to work best for me. Still took between 10-13 weeks from seed, but seemed to yield better. They seemed to enjoy a dark period for rest. Good luck.