ZFS is better than raw RAID, but 1 parity per 5 data disks is a pretty good match for the reliability you can expect out of any one machine.
Much more important than better parity is having backups. Maybe more important than having any parity, though if you have no parity please use JBOD and not RAID-0.
I'd almost always use RAID-1 or if I had > 4 disks, maybe RAID-6. RAID-5 seems very cost effective at first, but if you loose a drive the probability of losing another one in the restoring process is pretty high (I don't have the numbers, but I researched that years ago). The disk-replacement process produces very high load on the non defective disks and the more you have the riskier the process. Another aspect is that 5 drives draw way more power than 2 and you cannot (easily) upgrade the capacity, although ZFS offers a feature for RAID5-expansion.
Since RAID is not meant for backup, but for reliability, losing a drive while restoring will kill your storage pool and having to restore the whole data from a backup (e.g. from a cloud drive)is probably not what you want, since it takes time where the device is offline. If you rely on RAID5 without having a backup you're done.
So I have a RAID1, which is simple, reliable and easy to maintain. Replacing 2 drives with higher capacity ones and increasing the storage is easy.
I would run 2 or more parity disks always. I have had disks fail and rebuilding with only one parity drive is scary (have seen rebuilds go bad because a second drive failed whilst rebuilding).
Were those arrays doing regular scrubs, so that they experience rebuild-equivalent load every month or two and it's not a sudden shock to them?
If your odds of disk failure in a rebuild are "only" 10x normal failure rate, and it takes a week, 5 disks will all survive that week 98% of the time. That's plenty for a NAS.
If the drives are the same age and large parts of the drive haven't been read from for a long time until the rebuild you might find it already failed. Anecdotally around 12 years ago the chances of a second disk failing during a raid 5 rebuild (in our setup) was probably more like 10-20%
My goal isn't to be rude, but when you skip over a critical part of what I'm saying it causes a communication issue. Are you correcting my numbers, or intentionally giving numbers for a completely different scenario, or something in between? Is it none of those and you weren't taking my comment seriously enough to read 50 words? The way you replied made it hard to tell.
So I made a simple comment to point out the conflict, a little bit rude but not intended to escalate the level of rudeness, and easier for both of us than writing out a whole big thing.
What would you use instead?
ZFS is better than raw RAID, but 1 parity per 5 data disks is a pretty good match for the reliability you can expect out of any one machine.
Much more important than better parity is having backups. Maybe more important than having any parity, though if you have no parity please use JBOD and not RAID-0.