Unless you are having a specific problem or have a glaring security vulnerability that a particular update addresses, don't do it! Many times the new update will cause instability. In some rare cases, they can actually take away features with new software updates. I recall an older T-Mobile application that I previously used that allowed me to call Mexico for FREE. About ten years ago, TM pushed me a software upgrade for this AP that I did out of habit. As soon as I tried to call Mexico again, I found it was no longer possible for FREE. After consulting Google on the matter, it was clear that everyone who did this software upgrade immediately lost their ability to call Mexico for FREE. Those who ignored the upgrade could still take advantage of this feature. This is a rare case but an example of how doing an upgrade can also be a liability, not a benefit.
Ironically, one of the reasons I moved from my iPhone 6s+ to a Samsung Galaxy S8+ was the fact that my iPhone 6s was slowing down and the battery no longer took me through a day. I did not want to sacrifice my 3.5mm headset jack and did not see any upside to upgrading to an iPhone 7 or an iPhone 8 over my trusty 6s+. The X model cost double what the comparable S8+ did so this was a no-brainer for me.
Most of the updates I used to get were to address features like Apple Pay that I didn't even use. One of the problems with software upgrades is that Apple can be very cryptic when explaining what invulnerabilities were addressed. That's why my philosophy is, If it ain't broken, don't fix it!