On top of that some tools (I used fdformat) shifted the sectors to speed up sequential reads, i.e. have the first sector of the next track rotate in under the r/w head right as the head arrives.

Edit: another unrelated practice was buying up cheap(er) single-density disks, which were distinguished by the lack of a marker hole opposite the r/o protection slider, and used only one side of the medium for data. By drilling it out, one could trick the drives into using both sides, which usually worked out just fine. Mentioned here [1]

[1] https://en.wikipedia.org/wiki/Double-sided_disk

Ah yes, interleaving of the sectors. More prominant with early HD's and using tools like spinwrite to optimise the interleaving. Today it's all 1:1 as processing from the heads just been fast enough for decades to handle the speeds.

Spinwrite still exists, though in the early days/versions it was the golden tool for tuning up a system and could make huge differences. Like double your drive speed and more in some instances, but talking late 80's early 90's here when interleaving was thing and mid 90's 1:1 became the norm and made it moot. https://www.grc.com/Spinrite.htm

Single-density is not the same as single-sided. There are single-sided double-density disks.

I seem to recall having a program called "Twister" that could format disks like this.