Hi @Kilwillie,
I asked basically the same thing a while back about Synaptic which behaves the same as apt:
It's not like Mint which usually has an upgrade to the Updater that is done by itself first, before other updates. It's like the Updater code has to first get ready to handle the pending updates.
Instead, Ubuntu (and -Mate) has a combination of extra roll-out protection and bandwidth staggering on non-critical upgrades. You should never see this difference on critical or security updates.
Hope this makes sense.