I just remembered today, for some reason, the 2x F32T8 rapid start shoplight at my grandmother's old florist. When I was younger I didn't think anything of it, but thinking back that is a really unusual fixture! It had a rather slow rapid startup and two very mercury starved Altos that were basically uselessly bright especially since they were next to a window, but she used them every day and the new owner still does!

Does anyone know just how uncommon a 2x F32T8 RS setup is?

Originally when F32T8 was introduced in 1982, magnetic rapid start was pretty much the only way. By the early 90s, electronic T8 ballasts started to be more common and I think by the 2000s pretty much all T8 installs were electronic.

Magnetic T8 seems to be pretty uncommon, I only encountered one install in the wild. I think most places with the budget to upgrade to T8 was easily convinced to pay the extra for electronic ballasts. That said, I think Advance made magnetic T8 ballasts into the 2010s, only discontinuing them when most of their magnetic ballasts were discontinued.

I think magnetic T8 still served a purpose, areas sensitive to high frequency EMI would sometimes specify magnetic T8 instead of electronic T8. And if your building was all T8, magnetic T8 for those areas made more sense compared to stocking a small number of T12 lamps for that part.

Likewise. The only insyall I can think of in the wild was an airport terminal of all places (since renovated). Or maybe they were on T12 ballasts? They had the 60hz flicker but not the shimmer.

Can't say I've ever seen them in the wild either, at least not that I've known.  Even back in 1994, the first large T8 install that I saw used electronic ballasts.

I have a couple of fixtures that were originally T12 but converted to T8 and both had ballasts with date codes from 1993/1994. I suppose most building owners were content with using 34w T12 lamps and when budgets allow, convert to electronic T8 for more energy savings and flicker free operation over magnetic T8.

Granted, there were still some places with a lot of T12 in use here until the start of the 2020s, when they converted straight to LED and skipped T8 altogether.

I just remembered today, for some reason, the 2x F32T8 rapid start shoplight at my grandmother's old florist. When I was younger I didn't think anything of it, but thinking back that is a really unusual fixture! It had a rather slow rapid startup and two very mercury starved Altos that were basically uselessly bright especially since they were next to a window, but she used them every day and the new owner still does!

Does anyone know just how uncommon a 2x F32T8 RS setup is?

Magnetic rapid start or electronic rapid start? Magnetic ballast F32T8 is extremely rare.