Ive been runnings 5 gallons for a couple indoor harvests my temps and everything are more then fine and lighting but they take forever to dry out! so should i just use 3 gallons? i only veg for 4 weeks.
Why do you want them to dry out faster? I figured most would prefer to water less often? I'm not one, but still. I didn't do well with soil and watering "when the pot was light". I mean, that's exactly what I did, but I didn't like it. Wasn't routine enough for me. Plants needed water at different times, etc. My plants suffered from it.
I switched to coco, watered/fed daily. No issues. Faster growth and healthier plants.
That said, with all the sizes I've run up to 5 gal, I feel 5 is best overall. In my experience, anything smaller has the potential to require multiple feedings daily. Had that issue in soil, have it worse now in coco with 1,3 & 5 gallon pots going. 5 gal is good for 24 hrs, 3 gal gets fed at 6am & 6pm, 1 gal is suspended 1" deep into a bucket of bubbled nutes because she requires 3-4 feedings/day and I just can't do it. lol
Oh, I only veg for 4 weeks too but nature handles that as I'm running auto's.
You won't know what's best for you until you try.