I keep chains lubed, bearings packed, and things generally in adjustment, but don't get too carried away either on tour or at home.
My approach is pretty much the opposite of Peny's in that I try to clean chains as infrequently as possible. I do apply lube frequently and wipe it off but that is the extent of it. It seems to me that my chains last longer when I avoid cleaning with solvents or soap and water and only apply lube.
I keep an eye on wheel trueness and spoke tension, but only to the extent of spinning the wheel and looking for wobble or hop and plinking the spokes to see that they are fairly evenly tensioned. I do that now and then when it crosses my mind.
Shifter cable tension adjustment gets tweaked, most often while riding. Limit screws pretty much never get touched again once set up correctly.
Brake cable tension might get tweaked any time it needs it at any stop during the day, but it happens pretty rarely. Brake pads only get attention beyond a glance when there are starting to squeak, grind, or not work. That or if they are visibly close to worn out.
If going on a multi-month tour I am likely to give it a bit more of a preemptive going over, but even then don't get to carried away unless it has been a long time since I repacked bearings or something is close to end of life.
Truth be told, I do very little maintenance on tour.