OP: Do you vape the same flavor all day long, or switch it up? What about nic? 18mg all day? I try to keep a tank of my regular 18mg as well as a lower mg tank for when I find myself in that chain vape stage of the day, I'll switch to the lower nic and get my "vape" fix, then once I feel satisfied put the 18mg back on.
For example: When I first get to work we are closed so I have several hours of prep and vape time, so I use the lower nic because I know that regardless of nic strength I'm going to be chain vaping. Then once we open I only have a few opportunities throughout the night to step away to vape, so I vape the higher strength juice.
I realize this is not a direct answer to your question, but I think it might help to switch up the flavors and strengths so that you are not desensitized to the throat hit of vaping 18mg all day long. Also upping PG can help with throat hit, but you will sacrifice vapor. Also as far as menthol, as stated earlier it will simulate throat hit, but not give you any more actual throat hit. Once you vape some menthol you will understand that a little better.