yeast washing/reusing Do's and Don'ts

I am very new to reusing yeast and washing yeast but trying to learn as much about it as possible....for the simple fact of saving money.

My main questions are I think i heard washing and reusing a yeast like WLP 300 or 380 or any hefe yeast is not recommended. Is this correct? Are there any yeast strains that should be avoided?

I also heard you do not want to reuse yeast that was used to ferment big beers. If this is true what is highest OG that you would reuse the yeast from?

Last thing I need to know is how many batches can you keep washing yeast from until you should throw it away? Are you able to tell when the strain should be thrown away? Is this true in general or can you just keep rebuilding the strain...pitching and washing?

Thanks for the time to read this and help out. All of the things "i heard" was from someone at the local homebrew shop and he didn't seem too confident when he told me this. Thanks guys!

1. In general strains that are top cropped commercially are poor bottom croppers. WLP300 is a notoriously bad bottom cropper.

2. For me about 1.070 or 60 IBUs and I won't reuse. Most of my beers are under this so its not a problem. Russian River is basically making Pliny and Blind Pig at their production facility so they economically have to repitch from bigger beers, so it depends on what you brew.

3. Assuming you start with liquid yeast (anecdotally dry yeast can't be reused as much), you should get ten generations on average if your practices are good. This varies a lot by strain. In practice, you want to observe the fermentation characteristics and stop using it when it starts behaving differently.

thank you....that helps!