"Disk (drive) is cheap" ... so ... these days, swap, I typically do 1x to 4x RAM. But may also depend on use case scenario, etc. E.g. if I'm doing tmpfs filesystem(s), and depending how large and relative to RAM, I may add more swap. For systems that are relatively tight on RAM, I'll often do more swap.

And, conversely, for some systems I'd rather have crash and burn, and reboot, or spin up another, rather than have performance degrade when under major memory pressure, I may well go with no swap at all.

So ... does rather depend.

And most of the time for swap I'll do that on LVM, notably so I can fairly easily add (or reclaim and free) swap as and when may be relevant/appropriate - don't do a lot of fiddling with that, but sometimes for, e.g. some particular workloads or purposes, may be handy to balloon up the swap space ... then reclaim it later ... e.g. gonna use a ton of space on /tmp and that's tmpfs ... add swap, grow /tmp, and when done, reduce /tmp (yes, tmpfs can be reduced in size while it's mounted), then free up the excess swap that's no longer needed. Maybe a few times per year to once every couple of years or so I'll have some need/reason to do that - generally some specialized workload that needs lots of space for temporary filesystem storage, and where tmpfs is ideal for performance reasons.

Another random example, have a VM with only 1 GiB of RAM ... for reason(s) ... it has lots of swap, ... and with that it generally performs at least quite well enough ... even for the fair amount of work it's doing most all the time.

Your mileage will vary.