I don't read annual reports anymore, but that is not to discourage those who want to. I think every DIY investor should learn to read them.
I rely on the reaseach of others that is available on the internet and in libraries. Such sources supply me with a list of sound companies that I'm unlikely to lose money on, and likey to gain on all of them.
With that list in hand, I'm similiar to Rusty, as I use technical analysis to help me know when to buy. Once bought I plan to hold forever, unless the fundamental story changes for the worse.
In short, I don't spend hardly any time at all. which doesn't mean you shouldn't. You should research until you know you have done enough.