Talk:Abyssinal Armor Set/@comment-108.233.124.210-20131206031624/@comment-5166842-20131206145238

Each individual session lasts the same as they do outside grace, about 10 minutes, but overall the length of the grace period can be as little as 20-30 minutes (2-3 sessions) or can last well over an hour.

The more difficult gens last the longest, so it probably ends when a certain number of kills hit the server or something. A grace period will never end mid-session unless you get the kill though.