Here's a question for you Jim how many fonts do you use regularly. I mean I get that as this is your stock in tread you'll collect loads and use any number on accasion as needs require but out of interest how many do you have in your regular go to draw?
On a similar note but you have a rule of thumb for a maximum number if fonts you should use on a page (as few as possible in my head but I really don't know) or in any given comic (20 page american).
Apologise in advance if you've answered these before in one of your blogs and I'm just not remembering, or haven't seen it?
As you suggest, most letterers collect fonts like artists collect brushes and pens, and in the exact same way we probably rely on a dozen or fewer of 'em with the rest relegated to experimentation and the odd 'special' requirement.
If you've come from a hand-lettering background (like Annie) and have a custom font made from your hand-lettering, that's part of your USP as a letterer. If you're from a digital graphic design background (like me) then you're more likely to think in terms of picking a font for the tone/mood/look of each strip.
I try to stick to a very limited 'palette' of fonts for each project — one main dialogue font which hits what I think of as the tone for the project. I did a blog post about the thought process along these lines for
Zaucer of Zilk early in 2020.
As a basic rule of thumb, I have one dialogue font for a project (and maybe a handful of special 'voices', as with Demon Jenny and Salvatore in Diaboliks) and I try to keep sound effect fonts to maybe three per project. There'll be a 'heavy lifter' that serves for the bulk of the SFX and serves to keep the look consistent, a more ragged one for shattery or discordant FX, and usually one with a lighter weight for quiet FX. Possibly one with a 'blobby' look for spattery or squelchy FX.

So… on any given page, you'd be looking at one main font, maybe a special 'voice' and maybe a couple of the SFX fonts. Say, four fonts maximum. That's not say I've never done pages with more than four fonts, but if you're getting to five or six, it's probably time to ask yourself whether you really need to be using them all.*
On a very quick scan through the ten currently-open projects on my desktop, the 'main' fonts are as follows…
Durham Red: Out of Line BB
Fear Case: Out of Line BB
The Last Witch: CCMoritat
Space Riders: Anime Ace BB
Cherry Gilbert — Necromancer: Ready for Anything BB
Unfinished Corner: Ready for More BB
Proctor Valley Road: Heavy Mettle BB
Spectre Inspectors: CCVictorySpeech Lower
Roxy Rewind: Tight Spot BB
Abbott — 1973: CCHedgebackwards
So, you can see that that's nine different 'base' fonts over ten different books. Unusually, that list doesn't include Collect 'Em All BB, which in most weeks would be in play on at least one book (you can see it on Lawless and BOOM's Firefly books), or CCWildwords, which I use on Titan's Blade Runner titles.
There are some fonts in my library that I rarely use, but which I know are perfect for specific kinds of job. I like Blambot's Duty Calls BB a lot, but I think I've used it twice in ten years: once for the Porcelain books, and once for Megatropolis. Both projects have a heavy art nouveau/art deco aesthetic going on, and Duty Calls has elegant thin, tall characters, except for a wide, almost perfectly circular 'O', which echoes the typography common in those styles. I'd never use it for something like, say, Diaboliks, where Dom's art called for something a little blunter and, well,
blacker.
Phew. That was a ramble. I'm not sure if I've actually answered your question — sorry!
*Sometimes, the answer is 'yes'. There aren't many hard-and-fast rules for this sort of thing.