After extensive troubleshooting, innumerable head cleanings, and three print cartridges, it turned out the problem was not the print head at all, but the bargain cheap print cartridges I got from Amazon. Switching back to genuine Canon cartridges solved the "clogged print head" instantly.
After a bunch of testing, trying, et cetera. My printer returned to inconsistent results. Black printing was fine but colour was ‘iffy’ at best. So….I purchased a full set of Canon cartridges (the first time I ever heard my credit card say “Ouchâ€) and popped them in. I did a cleaning and the printer produced a flawless Test Print page.
I don't know about your Pixma, but my IP110 and it predecessor automatically run a head cleaning routine before printing any time it has been idle for more than a few hours so periodically running the head cleaning routines would only be called for, when print problems are noticed.
That sounds like a lot of ink consumption so I may do a cleaning once in a while or, barring that, periodically print the Test Print page to ensure that all colours flow through the print head and prevent drying up.
I have never used Canon cartridges since the originals ran out, although mine aren’t quite as “bargain†as the Amazon cartridges.
I’m going to assume that I can go back to my non-Canon cartridges once this set of Canons has got to empty. My printer was bought in 2012 so I figure, if it takes that long for the printer to react, I’ll be ready for a new one by 2024 anyway.