I quit doing Preacher Curls years ago.....very dangerous especially for an ego trainer......started deadlifting again but gave it up quickly.
Now I do Cable Preachers with a moderate weight with partials from the top and bottom at times to extend the set.
I`ve trained heavier than a muthafucker for a guy my size over the years, and it got me nowhere fast,except I did get stronger........3 bulging discs are no fun.
Now I train as heavy as I can for the reps I`m gunning for in my mind......no more singles,doubles, or triples etc.......an occasional set of 5 reps, and at my age that's probably not too smart but I do a lot more warning up these days.