Should I be doing this everytime I go out to the field or just after crashes and hard knocks? Ive heard both. Whats the best way to do it? Thanks

I would recommend that you do a range check every time you come out to the field. This will help prevent radio problems. Even though most of the time, radio equipment is damaged in a crash, it can also be damaged by regular hangar rash and knocks. Double checking every time at the field will only add to safety and economy.

Before every flying session.

Before each flight session. Fully collapse Tx antenna, start engine, walk 30 large paces (100 feet), and move sticks and look out for unusual twitching of all surfaces. Get a helper. If any unusual servo movement detected, locate source of problem and eliminate it first.......

Should check each flying day,also check plane controls,this is coming from a person that is a little lazy in this field,and I crashed my wild cat because I didn't check the controls and the transmitter was set for a plane I was flying earlier.

I do a range check each time I go to the field!
You want to look for inconsistencies!

Do a range check every time you go to the field. As said b4 go about 100 feet away with the antenna collapsed. And dont just wiggle the sticks. Move the sticks in a fluid and controlled manner, so you can see if the surfaces have and other type of movement on them suggesting a radio problem

One of the things I like about PCM is that you can program the rudder to go full to one side then just walk away until the receiver goes in failsafe. I just make sure that I continue to have the same range!