--adapt[=min=#,max=#]
zstd will dynamically adapt compression level to perceived I/O conditions. Compression level adaptation can be observed live by using command -v. Adaptation can be constrained between supplied
min and max levels. The feature works when combined with multi-threading and --long mode. It does not work with --single-thread. It sets window size to 8 MB by default (can be changed manu‐
ally, see wlog). Due to the chaotic nature of dynamic adaptation, compressed result is not reproducible.
This very much depends on your use case. I recently did the planet for zoom level 12 as I mentioned elsewhere on this article. I can go into details if you're interested.
Having JUST done this for zoom level 12 for the planet it's tedious. It took 9 days, to export to mbtiles, another 2 days going through pngcrush, and about 40 minutes to make it into a squashfs resulting in a 2.6G squashfs file which houses the 22,368,460 PNG files which are then served up directly via nginx in our case.