Well I already have a limit of 2 tops for myself set-- but I don't really wanna divide my 10 gallon until I can find a way that looks pretty and is functional. While it was nice having two fish before, the divider was some kind of eyesore imo.
If I devided again I'd want to take the time to get clear plastic or something with holes to let water through, and then use two of them with space between for a moss or something so that the bettas wouldn't constantly be stressed by each other.
But I'm lazy so I'll prolly just stick with one. xD