Well I've had a lot of old cars pass through my driveway. I've found the best thing to do with brakes is to replace everything that bends, moves, or jiggles at once. I hate the feel of brake fluid on my hands (and antifreeze) so if I have to open the system to do work then I do everything. This is more costly, but if I'm replacing a master cylinder doesn't it make sense to replace hoses? And then at that point you might as well do wheel cylinders/calipers also.
With cooling systems you need to replace water pumps before they go out. Thermostats need to be replaced regularly. And radiators go bad pretty quick if not kept full with the correct mix and good water. So I'll replace all that and all the hoses at once also. The way I look at is that everyone else would have paid 2-3 mechanics to look into their overheating problem ... I just spend the money on new parts instead of some jackass.