Right now I have a 10 gallon tank divided three ways. I plan on getting ghost shrimp sometime soon to help with mantinence but it's SO much easier then the 1 gallons I used to have the boys in. In the one gallons I'd have to take all the plants out, scoop out the betta, take the tank to the sink, dump the water and gravel into a strainer, fill the tank with water and dump until all the gravel was out, rinse the gravel, put it back in the tank, fill it back up with water, put the plants in, wait for the water to get to the right temp and then add the fish. Also there'd be unsightly bubbles for at least a day and I would get water everywhere.
Now all I have to do is a 50% water change once a week and run the gravel vacumn along the gravel to get out the debris. My suggestion though is not to buy an aquarium divider. Make one out of counted cross stich craft plastic. It's more durable and not nearly as see through. You can trim it to size too.