It's obvious that not everyone in your organisation requires E3 or E5's. You may have users that only need web-access for example, or only require an AD account and no Office at all!
When you first go into an organisation that has never done any user profiling and has purchased 'Full Suite for all!', it is a massive task to identify who is actually using what.
In the hope that I *may* be able to help or save you some time, here are bundle options that may help you save money on your next EA Anniversary date! Please note, we have the below options as we have to ensure we have 'Legal Hold' on our emails.
Standard User = Office E3, EM+S
Test User (no external email, but Office) = Office F1
Shared Machine (device license required) = Office 2016 Pro Plus with SA
Webmail only (no SharePoint access) = Exchange Online Plan 2
Webmail AND SharePoint Access = Exchange Online Plan 2, and Office F1
Don't look at your employee count and think that is how many Office 365 licenses you need. You'll end up wasting money!
Hope this helps,