Once you put on a bottom paint, then you will need to continue using it. Over time it builds up and becomes more difficult to keep it looking good. Been down that road and sorry I ever started doing it. Then I switched to wax or other quality protecting. Most do not require any buffing, just apply and forget it. Get yourself a pressure washer, even a cheap electric one will work as the wax keeps the crud from sticking. After you pressure wash the crud off then reapply the wax and go play. Depending on your body of water and how much crud there is, anywhere from a few weeks to six weeks do a pullout and clean. I use a spray on wax from Turtle wax, put it on heavy, no need to buff. When it is time to clean the hull a shot from the pressure washer removes the heavy stuff and a long handled car wash brush cleans off the rest. Rinse and let dry for a short time then spray on the wax. Takes mabey a couple hours at best, far less time and expense than painting, sanding and repainting. Also remember that crud will still stick to the bottom paint, you need to run the boat at speed to wash the crud off the bottom paint. Unless you go to great expense and time and effort most bottom paints will slow down your top speed, where the wax method usually increases your top speed if that is an issue.
