Entering together or entering apart

We've been told by people directing the lines that
a) When with UK husband (I'm a US citizen): go through UK line
b) When without UK husband: go through non-EU line.

However, I've been sent to the UK line when travelling by myself as well--it seems to depend on who is manning the desk that day, so I always just ask!

We've usually entered the UK together through the non-EU line because it's the shortest! They said they like to expedite the line.