I messed up my attempt at lining up the top of the cheek line

I've been there and it's well annoying. This is going to sound dumb... Something I've done for the past year or so is to take a thick rubber band and wrap it around my head. The rubber ensures it doesn't slip easily and if taut enough once adjusted it affords me a decent guide line that is repeatable. I also use it for my neckline; electric razor and then a straight razor to the band. Just make sure you don't bump the rubber band and use it as a visual guide rather than have it stop any razors etc.

Downside is I look like an absolute goon while doing it. Feels proper silly doing it but I thought I'd share just in case it helps anyone out.