As a lineholder/blockholder I would be in favor of a rotating reserve system. If memory serves me correctly AA has such a system for their reserves. The reserves need a chance to make money also and have a quality of life.
You are correct. This is the way reserve works at AA...
First 3 years of employment: 1 month on, 1 month off reserve.
After 3 years, you serve reserve 3 times/year until you have enough seniority to be totally off reserve--basically, 1 on, 3 off. If you are on the Dec-Apr-Aug reserve rotation, you can bid onto reserve in another month to change your rotation. (Of course, if you are really junior, senior people bidding on to your rotation to get off another rotation may bump you off (or back to Dec reserve, as the case may be

).
In more senior bases, someone might serve reserve only once or twice a year when they put more people on reserve in anticipation of high sick calls, etc. In other words, you are a lineholder (I think you call it blockholder) every month except November or December. And, if you are right on the border that month, you can try bidding OFF reserve which works sometimes.
The number of years it takes to be totally off reserve varies by base. At DFW, reserve may go over 20 years in some months. Traditionally, at LGA people were totally off reserve by year 3 or 4; however, with so few recalls since 9/11 and no new hires, reserve at LGA has been going to 15-16 years lately. (So, it is always possible to fall back onto the 1-on-3-off-rotation as the base seniority changes.)
When on reserve, you can pick up extra flying from the company or other f/as, but there are limitations.