Rationing places in oversubscibed events

This might sound like I'm trying to shoot myself in the foot but I'm coming round to the view that rationing places in popular oversubscibed events like the West Highland Way, Ben Nevis etc. might actually be good for the sport, good for the "old hands" race addicts, good for newcomers and good for race organisers.

I think that races like these have a very strong lure that brings folk back year after year. In recent years entering these races has become a real case of being "quick off the draw" and entering ASAP when the entry opens. This system tends to favour the race regulars who know the ropes and makes it hard for first timers to get a foot in the door. I think also that many race regulars would quite like to do something different some years but the lure of the race is too strong to resist and they end up doing the same race year after year without spreading their wings to attempt many of the other great races around.

I think I'd like to see repeat entries restricted to 2 entries every 3 or 4 years, with a withdrawal (that can be filled by someone else) not counting.

This would give race addicts a chance to have a year out and DO SOMETHING DIFFERENT! It would also free up a lot of race regulars for marshalling duties and give them a chance to give something back to a race that they may have run many times but not helped in the running of.
It would free up space for more first timers, which has got to be a good thing.

I can't think of a major downside at the moment but I'm sure others will come up with things I haven't thought of. ;-)