IMHO its a must. Me i make a lot of my own tooling because im doing weird crap most the time that a off the shelf solution is either unaffordable expensive or too big to fit in my limited space. Maintenance gets done as and when needed, some times i will drag it out a little say whilst ordering parts, but generally if there a problem on any of the tools its priority number 1 to fix it, again what i do i very much need everything up and working.
Making my own tooling often burns time and materials, but i have very very rarely ever regretted making tools for specific jobs. One man band every efficiency you get helps you do more work for the same effort next month.
IME and its been a sad fact i have seen play out way too many times, small companies have a few slower but good years and invest in equipment to build work - build customer base, they then pick up more work than they can cope with and stop investing in kit, sell off some of the lesser used stuff and to be fair generally continue to make good money for the next 3 or so years. Then the gravy chain comes to a end, customers end up going else were, the competition catches up and its game over.
My case a big reason for new kit is tax brakes too. Saving 29-40% on tax still makes new equipment far from free yes. But 99 times out of 100 it sure makes it easier to earn the same or more next year. Oftern times its the simple things too, having the right size spanners to grab whilst at a machine, more tool holders for both the lathe and mill etc. Little things can really bump productivity and a lot of it will pay off for the long term. One of the best things i got last year was a matching pair of 3 jaw removable top jaw chucks for the lathe, one lives on the lathe, the other on the mill table, like this i can turn a job in soft jaws then bring thoes same jaws over to the mill and do the milling on the parts gripping em in exactly the same way!