I'd agree with this (in spite of arguing against debuggers above). I was referring to my own development. In the case where you're handed someone else's spaghet

I'd agree with this (in spite of arguing against debuggers above). I was referring to my own development. In the case where you're handed someone else's spaghetti code and given the directive "fix this!", the fastest way to get up to speed on how things work is with a step-through debugger. That said, if you have the time I still think the best solution is to develop unit and functional tests (assuming none exist), and learning the code base that way.