What is the right sort of training varies depending on the sort of races you're training for, the time of year, and what your main targets are ( that is, when are the races you regard as your priorities). So during the off- season while building your base, you'll do more volume and lower intensity, then build up the intensity during your build period and back off dramatically on volume in order to peak for your big races. If all you do is intervals throughout the year I'd say you're missing out on building an endurance base, and if anyone is doing nothing but long, hard rides than I'd suggest they aren't training optimally either.

You need a training plan that brings you to your peak fitness when you need to be there, and that will involve both different regimes at different times of year, and a preparedness to back off at some points during the racing season - you can't stay at your peak for weeks at a time.

It's still quite difficult to beat Joe Friel's training bible. You don't mention whether you're training with a power meter, but even if you're using HR there's a lot in the book about training plans, periodization, the balance between volume and intensity and so on.