Talking pools in OpenZFS Mastery, which means yet again talking about blocks and sectors and alignment.
GPT partitions fill a number of sectors. If you partition a drive assuming 512-byte sectors, you can easily create a partition that would not cleanly start and end on 4K sector boundaries. Take a drive that has 4K sectors, but claims to have 512-byte sectors. Create a partition that fills, say, seven 512-byte sectors, then add another partition that fills the rest of the drive. Make a ZFS pool with 4K blocks on that large partition. Each filesystem block touches two physical sectors. The misalignment causes write amplification, destroying performance. For average spinning drives, assuming that all your disks use 4K physical sectors is safest. Certain SSDs also expect partitions to be aligned along 128 KB or 1 MB boundaries. Some enterprise drives use 8K sectors, however, and a handful of specialty devices even larger.
Avoid alignment problems. Make all GPT partitions begin and end on megabyte boundaries.
My whole stupid career is built on filesystems. You can still get your name in this book, though.