This is kind of a question no one can answer but yourself. There's too many variables in play, and everyone's life and drinking style is different. How many people are gong to be drinking your beer? How fast do you drink? How much variety do you want to have at any give time? How often do you plan on brewing? Do you EVER intend to bottle age some beers? Stuff like that. There's no rule of thumb for this.
I live alone, but I do brew a lot for fun, and even do a lot of small batch brewing , I have a lot of brewing friends and family that enjoys good beer so I nlike to share, but ultimately I will be drinking most of the beer myself. Lately I've been not drinking during the week, at least monday, tuesday and wednesday (and eating only meat and greens those days as well + working out.) I like variety, BUT I'm realistic enough to know that i'm the one who's going to be drinking most of the beer.I also believe that some beers can ONLY be bottle conditioned, so I still plan on bottling many batches, mostly big beers that need months and years to age.... I opted for a kenmore 7 cu freezer from Sears, it can hold 5 kegs with my 10" collar, but I chose as of now ONLY to have 3 beers on tap at any given time. This gives me room to cold crash or lager a fermenter in the keezer, OR just have 2 more kegs in reserve when my main kegs kick...
Eventually I might add a nitrogen tap for stouts, which will cut down my extra space by 1 keg. Which still would be ok.
There's no right or wrong answer to this. You're kinda gonna have to just figure this out for yourself. You can always have a bunch of full kegs stacked up in your closet full of beer and maturing while you drink whatever's in your keezer. Hit them with a little co2 to protect it and you're golden. It's no diifferent then bottling and having a pipeline.