It depends entirely on the individual. Some people are always on the "hunt," while others find a comfortable patch of audio goodness and stake their claim there for the long haul. I used to belong to the former camp, but for the last five years or so, I've been firmly in the latter. I know my system can be improved, and I may make a few small tweaks here and there to get me a little closer, but for the most part, the rig does the trick for me, and I haven't felt the need to make a big change in a long time. I think I got the fundamentals right, and that's a big step. If something blows up and I need to replace it, then that's a different matter! :)