If he only has two or three drinks, then he is not drinking too much (assuming that "too much" is defined as getting sick). You may think he drinks too often, but he does not drink too much.
If he only drinks on the weekend, but he gets blackout drunk every time, then he drinks too much.
And of course, if he has ten drinks every night, then he drinks too much and too often.
I know this is some really "no duh" kind of stuff here, but most people use "too much" for any kind of excess. When you realize that you have all of these little varieties with which to describe things, you will find that you can significantly drop the ambiguity in your writing, which increases your clarity, and makes you a more effective writer.