I think there should be a way to set a default invoice group for invoices and quotes, so that when you go to create a new invoice the drop down box automatically selects the default invoice group and when you create a new quote it selects the default quote group. If you have to make alot of invoices in one day it will save quite a bit of time.
You can already set this option at
System settings > Invoices > Default Invoice Group for invoices and
System settings > Quotes > Default Quote Group for quotes.