Length of pull is a very individual length. Some shooters prefer a longer length and some are more comfortable with a shorter length of pull. It is basically a comfort thing...whatever you are most comfortable with. I do believe it is very important for some freehand shooting competitions, like all shotgun sports and freehand rifle shooting. It seemes to me that it might be less important for prone shooting and Benchrest type shooting. In the last 2 categories a shorter than standard length might be more comfortable. That said, comfortable positioning is one of the keys common to all shooting sports. So if your rifle position feels ackward, you will not shoot as well as you would if you are perfectly comfortable. If extending or shortening your length of pull makes you more comfortable, you will hold your point of aim better and shoot more consistently.
My advise would be to measure your individual length of pull, then measure your rifle to see if there is a big difference. Then decide if you need to cut your stock. Alterately, try a rifle with a shorter length of pull or even an adjustable stock to see what feels the most comfortable to you.
To measure your individual length of pull for a right hand shooter, do as follows:
Hold a tape measure in you left hand.
With your right arm bent at 90 degrees, measure the length between the crook of your elbow to the first knuckle of your trigger finger. Some take it one step further and measure the same length only with the finger bent to 90 degrees (as if pulling the trigger). This will give you your standard length of pull. For most shooters it is between 13.5 and 14.5”. So for prone shooting, I would think a slightly shorter length of pull would be somewhat more comfortable. Many of the better stocks have alot of adjustment built in.
Finally, any good gunsmith can shorten most non-adjustable standard rifle stocks by removing the butt pad and cutting down the stock. Then they refit and re-install the butt (recoil) pad.
