Yesterday I bumbled my way through helping someone recover an old SCO Unix system that had crashed due to a disk failure. Twenty years ago and more I could do that sort of work while half asleep because I did it often, but the last time I did something as messy as this one was ten years ago and I was rusty then. Since then, I've forgotten a lot, so this job was not fun for me or the guy on the other end of the phone.
We did eventually get it done. I charged him a little over $100 an hour for my assistance, which is both way too high considering my rusty skills and yet also way too low because the system is 20 years old and who else is going to do it? Most of the people who ever knew anything about this stuff are now at retirement age and are just as rusty as I am. They MIGHT have been able to find someone with a better memory, but who says they'd have charged any less even if they did get it done faster than the three hours I spent.
Then last night someone called me needing on-site assistance with a similarly ancient Linux system. I remember even less about 1990's Linux than 1990's SCO Unix, so I quoted him $175.00/hour plus .95/mile round trip with a minimum 2 hours on site and told him that because my memory of that ancient stuff is poor, it could easily run a full day for something that should be much quicker. I was very honest with him: I told him that I don't really want the work because it will be painful for both me and him.
These are very strange feelings! Again, I'm both over and under charging!