My first exec chef was like that, a C.I.A trained chef who had at least 30 ring binders of recipes in his office, he said "I can't teach you to be a specialist in anything, but I can teach you a bit about everything" back when I dreamed of being a saucier.. Haha.
Anyway you should pick up a copy of La Rousse Gastronomique, they have all the beurre sauces, I don't cook French anymore, which is pretty much where butter in everything originates from.
As said above ive only used it by itself to finish a sauce last minute and off the heat.
You could try a beurre marnie 1:1 melted butter to flour, you can roll it in cling film in a cylinder it refrigerate it, then cut it into tablespoon discs as needed. This is obviously the predecessor to the roux, just remember its uncooked flour so will need to be added with enough time to be simmered for a bit.