Does anyone know how long it takes for the guard flag to come back after a multi-day relay downtime?

Know that WTU (weighted time up) is 98%, and new-relay TK (time known) minimum is eight days.

Reading rephist.c the the WTU is calculated from uptime history but rather then spend awhile to fully understand it seemed worth asking.

Presently watching a relay that has been around six weeks, has been down four days recently and five total, has 14-day 100% uptime, Globe- calculated 1-month uptime of 85% and 3-month uptime of 90%. Had guard a couple of times but has not seen it return after the last outage.