I built a village as a single large building (35x35, with varying sections), with a downstairs for job site blocks and upstairs for housing. Once the villagers claimed their beds in the upstairs level, they continued their job for several days before giving up and just hanging out in their rooms. The time it took for the villager to forget the job site block varied. I believe this may be due to a pathfinding limitation, but I'm not entirely sure. According to the wiki, villagers are able to pathfind job blocks for anything within a 48 block radius. However, upon testing, it turns out that this appears to be a walked distance of 48 blocks, rather than a radius of a spherical distance.