After I finished the Wainwrights, it made a nice change to just go and explore wherever I felt like, visiting some old favourites that I hadn't seen for a while. After a while I got bored with going where I pleased though, and started looking for another agenda to motivate my choices, so I started working on Birketts and Nuttalls tick lists, but not so single mindedly. After my fitness started to fail I turned my attention to the Marilyns, but I didn't get much farther than ticking off the ones I had already done.
The point about tick lists taking you places you wouldn't have otherwise gone is a good one. When I switched from walking to cycling I felt in need of an objective, so I started trying to tick off all the youth hostels in the YHA handbook, and it took me into areas I wouldn't have given a second thought to in my walking days. (Ticking off hostels keeps you busy, because it's a moving target!)