Question about life cycle of mother plant

I've read some saying an old plant loses its potency (taking a clone from say a 10 year old mother) vs taking a clone to replace the mother annually and flowering out the mother.

I've also watched documentary where they say they are taking clones from a 40 year old plant still....

I'm going to be starting a personal perpetual indoor grow with 4 plants, basically want to know do I keep mothers forever and just clone/prune to keep their size or regrow them with their clones for the best potency?

Anyone with actual knowledge of this can chime in?

I've heard some very respected growers state that they find better results by cycling their mothers out as opposed to holding on to them for many seasons. It seems that the general consensus is that they lose that potency/vigor over time. Hard fact to prove though!