As you said, it definitely depends on the pattern. However, I just finished my first sweater, and I made myself the medium, and it took just about 4 and a half skeins of Cascade Pastaza. That's a bulky yarn and it was on large needles, but it sure didn't take up very much yarn. So I'd just pick a pattern I loved, double check the yarn substitution and everything, and if you have a good deal more than enough, go ahead and make it. Always good to make sure you have more than enough though, esp. if you're substituting. Good luck!!!