I get a certain strain up and running (ale or lager) and then I brew consecutive batches with that yeast and the yeast never sits for any longer than about 2-3 weeks. In that amount of time, the yeast can just be pitched .. no starter required. I did try to start saving A LOT of strains but eventually I realized that they didn't come back the way I expected so I stopped that. I leave my harvested yeast in a 1000ml flask with sanitized foil over the top and in the fridge .. and I do the same thing .. I run the beer off into the keg and then I have this same flask which (because I'm a little OCD about yeast) has had boiling water added to it and then it sits in Starsan for 10 minutes or so. Then swirl the yeast in the fermenter and pour it through a sanitized funnel, into the flask and then covered with sanitized foil until the next batch. Yes I will have a lot of beer made with the same yeast so I try to mix it up .. smoother, hoppier, pale, amber, darker, different hops, etc.