Our company high recommends 2 visits per year and our agreement clients all get that included. As far as the Trane Clean Effects, it has an electronic air cleaner. Read the EPA info on electronic air cleaners. They do a great job the first 30 days and then tank quickly as time goes on. The only way to rejuvenate them is with chemicals, a thorough rinse & dry, then reinsert the cells. Most people don't want to pay the freight for monthly visits so Trane is recommending 4 times a year. The problem is, there's only one company out of 100 that actually carries the chemical to properly clean an EAC. Oh I know, the manufacturer says you can put the cells in the dishwasher and clean them. Hey, wake up. If the EAC is really doing it's job, it's baking the residue onto the cells just like food spilled in an oven. Ever try to clean an oven with soap and water? Doesn't happen unless you're talking about a self cleaning oven. I doubt you've got a 600^F dishwasher with a 3 hour cycle on it like a self cleaning oven. Chemicals are the only way to clean the oven and likewise the only way to clean the average EAC. The manufacture says use the dishwasher because they'd never sell the highly profitable EAC if they told the truth. Okay, so what to do? We use the Dynamic EAC. It's 1-inch thick, replaces the existing air filter and for servicing, you take out the inner element, vacuum off the rock stopper frame and insert a totally new cell as often as you like. I have one in my home as well as having installed them in hundreds of other homes. Everyone loves them and we sell them a new 4-pack of elements (cells) every year.