How often is "getting to the range enough"?

In the chat during last night's Gun Nuts Radio, someone posed the question: what does it mean to get to the range enough? How often do you think you should go to get as good as you want?

I'd like to repeatably get thumb-sized groupings at 25 feet for slow fire, and palm sized groups at 25 feet for quick fire.

I only got into shooting three years ago. Not counting the few dozen trigger pulls as a kid, plinking with my friends, I have fewer than 2000 rounds sent down range. Not a lot, and certainly not enough to become more than - at best - a passable shot.

Now it's quite a hike to get to the range. Since it's a production to get there, I don't go often. One result is that I don't shoot much .22. When a man has a hankering for Recoil Therapy, he's looking for a little more therapy than a .22 will serve up, if you know what I mean.

Ideally, I'd go twice a month, a hundred rounds a session, 2500 a year or so. Combined with the Airsoft 1911 in the basement for recoil-less practice (perhaps 1000 trigger pulls a month), this might almost be enough.