Indeed, which is why I'm likely to not put that into the same basket as domain renewals.

One of my hosting providers (DigitalOcean) provides DNS services I can use freely with my account, for example. So really I could just move all the DNS there and then chop and change where the domains are registered pretty much based on price alone. One disadvantage of DO used to be that their DNS doesn't update quickly, although a quick test now suggests that's not an issue any more (or I misremember it).

The reason cost matters is that I have quite a lot of domains, a lot of them not heavily used (for example .uk domains that redirect to .co.uk) or just for email forwarding (which for the most part I'm happy to let the domain provider manage).