How much is in the jars? If it's a full 8 oz, I would use less. Much less.
Tom, what's the downside of using 6-8 oz.? Less healthy yeast?
6 oz of yeast is about 5 white labs vials. That is a lot to add to a one liter starter, and for a 3 gallon batch. I don't know if there's a huge downside really, but it's just not necessary and I would stick with more conventional pitching rates.
I don't worry about yeast health per volume like that - you have more unhealthy yeast, but more healthy yeast too. If it is a fresh and healthy slurry, I'd skip the starter and just direct pitch an appropriate amount of yeast. If you are worried about the health of the yeast, like if it's been sitting around for a while, then make a starter of appropriate volume and pitching rate for the beer you're making. But I would use a bigger starter, that much yeast in 1 liter isn't going to give you much growth, if any, and might not really be energizing your yeast.
A fresh 6 oz slurry of yeast is more than enough for 5 gallons of a 1.100 beer, in 3 gallons it should be enough for anything Fred would throw it in
This all assumes ales of course, lager pitching rates will be higher. And seriously Lennie, if you like your beers then don't change on my account.