It all depends upon the beer...I kinda like 10 for beers that might stand a chance at holding up that long...at least 4 IMO...or if the beer might be heading downhill, 3...I could see that perhaps my Avery Beast could make it that long, but sheesh 10 yr old beer. I think beer
is made to be consumed. Ah I got to wait 2 more for that Avery Beast to get ripe...then prolly gonna have
a taste just because. That is not a vertical taste either....just a reserved special bottle.
At GABF a few years ago, Alaska Brewing was doing vertical tastings of their Smoked Porter. They had 4 different vintages each session. I was there on the Thursday night session and enjoyed a 10 year old sample compared with more recent ones. It was the highlight of the evening for me. The oldest example was pretty vinous (winey), but it was cool to taste the progression.