Hate it when client demands a small specific change and doing what requires a lot of modifications in the code.

Being self employed, I get this on projects. The key to not going insane is to tie down the spec and budget making it clear about changes (change control) up front and a water tight contract. I am always flexible and will discuss changes. I document the changes and how they will affect the project in terms of cost and deadline. Keeping the client onside makes for an easier life. If deadlines and budget are fixed, you can suggest a phase 2 further down the line. Of course some clients are real wankers, so you need to asses your relationship with them and work on an exit strategy. Shit clients will always be shit and cost you money/sanity and take your focus off good clients. If you work somewhere then the PM should do his/her job properly.

It should only take 10mins though, right?

@helloworld - great comment. Worth it's weight in gold.