Hi again Matt. Just to add a bit to Ryan's great post, cycling a few weeks of fast pace lighter (I call it METCON for Metabolic CONditioning) with a period of heavier, slower pace stuff (lets call if ME for Max Effort) is classic periodization, and is a good way to get the best of both worlds, so when you are in the METCON mode, don't worry about the weight, and conversly, when in the ME mode, don't worry about the pace. You will find the METCONdrastically increases your work capacity. This type of cycling is well known, and is the classic model.
However, if you are like me, and others, you might get bored doing just one type of thing. I like to use the crossfit model of 3 on, 1 off, repeat, doing METCON,ME,METCON, off , repeatand that way I never really lose touch with either method. For more reovery, you could always do METCON, ME, off, METCON, METCON, off, ME, METCON, or however you choose to configure it. Nothing is written in stone, just go by how your body reacts.