When increasing mileage, it might be better to alternate high weeks with low weeks, particularly when the runners in question are young. That strategy seems to best follow a stimulation/adaptation scheme. Actually, VERY young runners (jr. high) can use only 2-4 days "high" (not TOO high at that age) followed by 4 or more days low. As they progress through HS, they can go to high and low WEEKS. There's not really anything special about using WEEKS from a physiological standpoint; it's just that the structure of daily life for a HS or college runner makes it easier to do things like place long runs on weekends and to divide the schedule into 7-day blocks.
The high week/low week plan can be used as long as increases in mileage are taking place (i.e., preseasons) and might be continued for a few weeks during the season since the stress of school is added to the routine. I tend to think in terms of a CAREER rather than a SEASON, so there's plenty of time to work from a high week/low week routine up to several high weeks in a row. Once a runner of college age has become COMFORTABLE with a particular mileage level (and has adapted to school life) within a season, I guess it's fine to stay at that mileage for several weeks in a row before dropping down for a low week (perhaps prior to a big meet).
Consistency of training can still occur within a high week/low week framework, since low weeks can still have a few high DAYS in them (just not as many as in a high week). Consistency doesn't have to preclude quality, either. It just has to do with what the NATURE of the training is. "Quality" training involves high-end aerobic running as the principal "hard" days (with some short strides thrown in every so often for neuromuscular specificity). Tougher anaerobic training (or "speed-endurance" stuff such as 8-10 hard quarters) can't be ignored, but should be used sparingly.
As far as MILEAGE consistency is concerned, my view is that it's best to wait until AFTER college to run high week after high week, ideally having worked up to that routine over the years. It's only at that stage of the game that you can design your own race schedule and can make sure you're following a more individualized routine.