I have zilch experience of kegging and only experienced with bottle conditioning. First off, whether and to what extent beer will improve with age really depends on the type of beer. A barley wine will have longevity as well as needing time to develop, a raspberry wheat beer, not. Bottled beer most of the time will have residual yeast (unless you have a very fancy set up, which will likely mean you also keg) which will drive what happens in the bottle. After a while the flavour, aroma, mouthfeel, carbonation etc will deteriorate from the optimum. But until it does the yeast enhances, in my opinion, the quality of the beer. In a homebrew environment that generally makes for earlier drinking.
I am just going from my experience, and the beer style is another key consideration. I love Proper Job and have a pretty good clone recipe, honed over many attempts, including using yeast St Austell’s Brewery very kindly gave to me. I saved a bottle from an excellent batch for my brother. What with C-19, we never met up and I drank it after 5/6 months. It was **** and nothing like the nectar it was at 2 months. By comparison, I had a last bottle of Dusseldorf Altbier recently that was 8 months old and it was pure silk, the best one. Just lovely. I put that longevity down to extended lagering. I will be making that one again and exercising restraint!
Basically, follow your palate. That’s the best test. In terms of bottled ales, experience tells me to sup (in most cases) within circa 3 months from bottling.
