[MNWayne]

From day one with new yeast, I overbuilt a starter, at high krausen I collected one pint in a sanitized mason jar and stored it in the fridge, and used the starter. The day before each batch I remove the sample from fridge, let it warm up, pitch it in 1.040 starter, being sure to make a pint too much, and repeat the process. I've been at it now for over a year, 30-40 batches. Any advantage to refreshing the strain?

[Robert]

Not if it's doing the job as you like.

[Slowbrew]

Yeast like to mutate but as long as the batch you have is giving you the results you want there's no reason to stop. 

Someday, you may find your yeast has changed in a way you don't like and if that happens then get new yeast. 

It's more likely that it will just settle into your brewery and become your strain, not quite what you started with, but doing exactly what you want.  That's how the really old yeasts came to be.  One brewery reusing the same strain until it became their "house yeast".

IMHO

Paul

[ynotbrusum]

I went 25 re-pitches with the same lager yeast over about 2 years without issue, until I simply wanted to try something different.  Now I repitch a few times on occasion, depending on the strain.  YMMV and the house strain idea is perfectly worthwhile.