I think that if I were to let Lacey's hooves get long enough to where I could nip, her hooves would have majorly overgrown. I mean, I take her all the way to the white line on most of her hoof and even with doing that every two or so weeks, I still get little flares here and there.
You could, of course, try for a few trims but I think you'll find it easier to keep on top of everything if you just do a little rasping once every one or two weeks... :)
ETA - I did discover that once I started following the white line, her soles REALLY changed. We had a major sole shed-out during the first month or two that I was doing her hooves myself. While her sole was shedding, I was rasping every week, sometimes more. Now I'm more comfortable that her sole is "accurate" but it is still stretched and warped in a few places that seem to be slowly working themselves out as I continue to follow the WL.