To whom it may concern:
I feel like the time it takes for my HA pair to fail-over from master to standby and vice-versa while upgrading is taking too longer; it is OK to reduce the 9-s default to the minimum limit of 3-s. The reason I ask, is that it's especially troublesome for our production environment even in low usage time where am waiting for the standby machine to kick in...
P.S. I would assume if there is a temporary glitch (i.e. more than 3 seconds) in the primary pair during the day and then of-course it will switch to the secondary; had a similar issue with my ohter F5 devices