The old "write this in the margin but it's not official" game (elders book) that we got from the CO from time to time at elders meetings said 2/3 years of inactivity was about right for not chasing up "serious wrongdoing" unless it disturbed the congregation. (italics mine)
But if there is a spouse in who wants to remarry "scripturally" beating the drum and getting the elders to dance that can extend for many years - even for life!