You are suppose to clean them every 2 months. I clean mine 2 times a year. All makes and models are different. Mine is Sears. If you have allergies, you will notice more than if you don't.
You can now buy filters that filter down to microns. They cost as much as $10 each. They probably work as well or even better than an EAC, but add up the cost $100 per year.
I clean my EAC elements it a laundary tub using automatic dishwasher detergent. You cannot use oil-based soaps. It takes 2 hours each cleaning. If you don't want to be bothered cleaning then spend $100 a year on expensive paper filters.
I wonder how much the micron air filters reduce airflow?
I think most of its overkill unless you have severe allergies. Unless the furnace and duct system is 100 airtight, you'll get some dust anyway. You will be filtering micron particles at the cold air returns, and sucking larger particles past the furnace access door.
In summary, EACs are nice, but don't expect a miracle.