We clearly live in very different worlds as far as what our needs/wants are. The amount of time a backup takes is generally irrelevant to me as these are done overnight. It's no slower or faster based on drive size, but actual drive space used, as that's all that gets backed up, but having the extra space if/when you need it is really useful. That's why my two latest laptops both have 2TB HDDs as their one and only onboard drives. I also like to allow a HDD to have lots of "breathing space" on it as well as I've suffered through severe sluggishness (long ago, actually) on a machine where a smaller HDD got far too close to full to allow Windows the space it needs during the normal course of events.
If one does incremental backups, which I do approximately every 2 months, on average, for about a year before doing another baseline full system backup, the incrementals are much faster than the initial full system image. Of course, if I had to restore using incremental backups it would be much slower. You are going to trade off speed at the backup time or the restore time. If restore time is critical then it's better to take full system image backups as a matter of course since they're the easiest, quickest, and least likely to have any issues to recover from.
There is no right or wrong answer to "Big" vs. "Small." One needs to analyze one's own wants and needs to make that decision, and the time for backup or recovery would be way, way down on my list of things to consider.
Brian AKA Bri the Tech Guy (my website address is in my profile) Windows 10 Home, 64-bit, Version 1709, Build 16299
Here is a test to find out whether your mission in life is complete. If you’re alive, it isn’t.
~ Lauren Bacall