Update with USB?

[Grizzly]

Hi

I have a few Ubuntu PC's (2 x Desktop, 2 x Laptop & 1 x Netbook) all runing 
Trusty LTS (various states of upgrade/update) I would like to download the 
latest ISO then use that to do the upgrades/updates, especially with Xenial 
Xerus due out soon

My BroadBand is slow (650k ish) so doing them all

sudo apt-get update -y  && sudo apt-get -y dist-upgrade 
And
sudo do-release-upgrade 

is a PITA

So can it work from LIVE USB