True enough, but I think anyone that has to ask a general question like this would benefit from overall fitness gains and doesn't need anything more complicated . You won't really know what you really need to specifically train (and I sure as heck don't) until you get a powermeter and can see where your strengths and weaknesses lie. Then you can train specific things like threshold power, hill climbing, sprinting, etc. Until then, I think general high intensity intervals will do you as much good as anything else.