Losing /Focus in WoW

So I can't figure out what causes it yet, just haven't really tried, but I tend to use /focus <primary character>. Then /assist focus to attack. This way I can /cast [target=focus] heal, and keep the target to support DPS... Anyways I'm finding I lose my /focus at some point while playing. not sure if it's zoning, or after a certain amount of time. I'll see if I can track it down. and let me know if anyone else is noticing this or not. I do know prepatch my focus target stayed the same the entire time the character was logged on. You would only lose who your focus was upon exiting the game. Not just logging out, but actually exiting WoW if I recall correctly...

They changed it but I used to use /assist Xzin and then /cast then TargetLastTarget();.

Now they changed it to be /targetlasttarget. Same basic functionality but it is protected code so harder to manipulate from an API perspective.

I am looking to try focus as I will be able to modify the focus on the fly (like when my main character dies). My new setup is changing the focus from being Xzin centric to being able to be controlled by any character.

I'm working on this part now. I'm running three accounts. I need to be able to jump from each one and them assist easily.

Could either of you post your macro?

Can't you just reset focus from time to time when you /follow?

I think I have a working solution. I made a macro that changes the focus for each character to themselves. When I switch to a different character, I hit the corresponding macro. I can easily change it on the fly depending what character I'm on. I use AHK and assigned the same key bind to all three accounts