Excellent question. Here’s kind of how I formulate a grist for any recipe (in no particular order):
5-15% Crystal or caramel malts (this includes honey malt, perhaps a few others), depending on how sweet and/or caramelly you want it.
15-40% Rye, depending on how much flavor and body you want. It will also give a VERY creamy head.
5% Munich feels best for a pale ale, 10% might be a little too much. This of course is very style dependent. For example, you can use up to 100% Munich in a dunkel lager. But for most other styles, 5-10% is probably about as much Munich as you’d ever want or need.
As a related option, you can go much higher with Vienna, up to 100% as the base malt if you wanted to. It’s sort of like a milder version of Munich, or a very bready & toasty version of standard 2-row.
If you were to use any wheat, most people use anywhere from 10-60%, depending on how much wheaty flavor and creamy head you want. However I see no reason why you couldn’t take it to 100% if you wanted. Just need to add a couple pounds of rice hulls to prevent a stuck runoff and sparge.
Most other biscuit malts, roasted/black malts, aromatic, melanoidin, victory, etc. should be limited way down to 4-5% maximum, but typically you might use closer to 2-3%. These are the strongest malts and if you use too much, you might regret it.
And so, for any recipe, whatever percentage is left after all that is for your base malt, which could be 2-row, pilsner malt, Maris Otter, Vienna, etc. For any typical batch in any typical recipe, this can be anywhere from about 30% to 100%. 60 to 70% is probably most common, but it varies a lot between recipes. In fact this makes me wonder…
People don’t seem to give base malts enough credit in general. Think about it – the right base malt is the foundation of any great recipe. The base malt will truly provide a ton of flavor all by itself. But if you use too many specialty malts, it dilutes the most basic, “beery”, malty flavor of your recipe. Fundamentally I think I’d try to keep the base malt percentage >50% or even 60% as a general rule, and higher might be even better. Otherwise, all the different specialty malts may create a sort of muddled mess without legs to stand on, to the point of really not tasting much like beer anymore, but more of a worty soup with alcohol. I think a good beer needs a strong base malt presence, which gives the beer much of its “beery” character. The desire should NOT be to create a smorgasbord of every specialty malt that might be good in your recipe. I think it’s best to keep recipes as simple as possible. You can play around with 10 specialty malts over time from batch to batch, but in any one batch, you should limit your specialty malts to 2 or maybe 3 max, in my very humble opinion. On the other hand… I’m sure I have won awards with recipes having 5 or 6 specialty malts. But are all those different malts really truly needed? I am thinking not. So anyway…