Well in the lower base ranges, which is what I am doing now. I am on the rollers 7 days a week, anhour to and hour and a half, zone 2. I try to keep the HR in check while keeping the highest speed.

One thing to keep in mind if you want to improve via a long base (and I'm not pretending to be a pro here just following what's in the friel book) is to do increased resistence in base. Therefore, I normally ride outdoors in a gear that would let my cadence be 105, but during base I gear up so that I am pushing higher restience and a cadence range of 90-95. Getting "better" to me means getting more powerful and this seems to help a lot.

Also remember to do ample recovery so you aren't working against yourself