Understanding 'MobileSoftwareUpdateErrorDomain error 78' during iOS updates

What’s that means ”MobileSoftwareUpdateErrorDomain error 78 - update finish took too long…”? Is update took about a hour from IOS 26.0.1 to IOS 26.1 normal? Can update took about 2 Gb difference storage space between two different iPhones? Same update from IOS 26.1 to IOS 26.2. One took 3.16Gb, the other one only 1.15Gb.

[Re-Titled by Moderator]