If you're asking genuinely then I can tell you my experience when I was part of a SaaS shop, though the times have changed a lot and "my metric is not necessarily your metric".

But it was roughly "one large impact a month, for six months", with large caveats that upper management for whatever company had to be working with the product during that month.

Large companies don't care if X service went out during the night and impacted someone not in their timezone.

If the CTO notices that he can't use something with the same regularity that he gets paid, then it doesn't take long for it to stick in their mind. But migrating everything is _so painful_ that the majority of large companies will do anything they can to avoid moving away.