yeah, I mean, bettas are territorial, and I think more unessacary space stresses them out to "patrol" I think as long as the water quality is good and the temp is around 78, then they do great.
2 Gallons is what I consider best, but 1 gallon is good too if you are willing to change water a lot.
My lights keep my water temp good on my for the most part, but at night I do turn a heater on... if the room is kinda of cool. Summer is here, so my room is kept kinda hot lol. So they are good.
but thanks :)