I think that it does ebb and flow some. I didn't buy a flashlight for well over a year after I bought a bunch of things, figured out what really worked for me day to day, and settled on 4 flashlights (not including old D mags). That has only been mildly disrupted by the Cree/Seoul/Rebel introductions which have had me thinking about new lights or modding some old lights. But I'm still pretty happy with my Streamlight Strion (high power, full spectrum and "free" lumens), HDS EDC B42 (covers most bases other than EDC pocket light since I wear business casual attire most days and it is a little big for dress pants pockets), Peak Pacific CR2 (EDC pocket carry) and a Photon microlight II as my last ditch keychain backup light.
These still serve me well and while I've been getting up to speed on the dizzying range of multi level lights on the market that are not my old standby Streamlight, Surefire, Arc, Peak, HDS, Inova lights - I haven't really figured out a deficiency in my current setup that has me chomping at the bit to buy something new.
But I have been seriously considering a Seoul upgrade for my HDS - which I still love but for a relatively small price I could get better than Novatac 80 performance and close to 120 performance for a lot less money. Oddly, the increased brightness on the lowest level, which I use a lot, is something of a disincentive for me moreso than the oomph of the max and primary levels. I would probably use secondary more, however, and would experience some real runtime gains...