How long do you let your mother go?

I've been running this strawberry sour diesel strain for awhile now. Kept a SSD mother plant in veg for over a year now & it seems like her offspring are not as vibrant as they once were. I've got a bunch of new strains started from seed in flower now & they are much frostier & more pungent smelling than the SSD clones are. How long before a mother plant begins to show her age? Should I bother to put her in the flower room or just toss her in the compost bin?

6 months is a good time to veg a cuple of clones for new mothers.
I always flower the mothers, no matter how old. Alot of bud there.

Yeah I took these plants to 11 weeks but in the past I've pulled them much earlier like 9 weeks. These took a long time to mature & I guess the first plant I pulled was not as far along as I thought- bottom nuggets are weak as fuck; still too green I guess. I hate to waste my mother so I will flower her out & start anew- luckily still have 1 SSD seed left.