I have never been a big fan of growth limitation by-laws that make a very small number of building permits available. Especially egregious are ones that make a small number available just once a year. Generally, the result is a small number of builders being able to obtain the right to build within a community.
The Eliot example, while providing for 20% of the permits for affordable housing, still limits growth to less than half a percent. And, limits affordable housing creation to about a tenth of a percent of total housing. While moratoria may be necessary for short periods of time, long term building limits, as are typical in New Hampshire and Maine, serve little real purpose.