At the risk of asking a "too open ended question" I'm giving it a try:
I'm running into more and more situations where I have to decide to either use a module that does a lot more than what I need or just writing my own code or template mod.
For example, the password policy has features that I need, but also has a lot that I don't. The 47kb zip file size tells me that it's a lot of code for my small problem. I implemented my own password policy with less than 20 lines of code in a hook.
I'm trying to limit the total amount of modules installed to a max of around 100. However, since signups don't happen that frequently this module probably won't affect the overall site performance.
Does anyone have specific recommendations on when to use a module vs. writing own code? Especially when better runtime performance and reduced overall complexity are the main goals.