I clean mine once per year. My car is garaged. If it was outside all the time, I'd do it twice a year.
I avoid disconnecting the plastic intake tube from the shaker itself. It's a snap fit and I don't want to risk breaking any plastic bits that hold it on.
If you've never removed the shaker, it's held on by two 10mm bolts, one on each side. The bolts are under the raised bump in the rubber tray on the right and left of the shaker. The bumps provide clearance for bolt access.
(Oops. I forgot. Disconnect the two water drain tubes from the shaker/ rubber. Look for the brass drain on top of the rubber tray - driver's side.)
Once the bolts are removed, put your hand in the mouth of the shaker and yank up gently but firmly. The bottom of the shaker has four nylon sockets that snap into four steel ***** on the steel mount. Once the front is separated. put one hand on either side towards the rear of the shaker and pull up.
(I have a C&L intake and I don't remember if the stock plastic shield around the stock air filter is bolted to the inner fender well. If it is, be sure you remove the bolt or other fasteners.)
At this point, you can lift the shaker, plastic air inlet tube and air filter shield off the car. There are four bolts on the bottom of the shaker. Undo them and the shaker separates horizontally with the rubber tray in between.
I use Meguiar's APC+ (All Purpose Cleaner) diluted 1 part cleaner and 10
parts water to clean the inside of the shaker and spray water through the still connected plastic air inlet tube.
Again, I'm not running the stock air filter or plastic container. If you are, remove the air filter before running water through the tube.
Use pressurized air to dry the tube or let it air dry before reassembly.
I always find bugs and debris on the side of my air filter opposite the air inlet tube. That's the stuff caught by the shaker and shoved down the air inlet tube, so I'm positive there's crap coming through the system.