You can do this to some extent, but its also really useful if you can to plan at least roughly what recipies you're likely to do as well. I've got quite a few well-past it grains from trying to cover a generic range, and yet 'at the same time' not had what I wanted for quite a few recipies. It also depends if you want to follow existing recipies or make your own up, as to what range you 'need' rather than can get by with.
But yes, for traditional british ales include masses of pale malt and crystal in reasonable quantity plus some wheat and a tad of black and chocolate malt, and a little roasted barley is good for stouts. For european beers I find munich and lager malt are common staples too, and of course for wheat beers around 60% wheat malt or so is typical. I find that these days I'm using munich in more malty british styles too though, supplanting some of the crystal.
Cheers
kev