I train in cycles so reps vary in each cycle.
Also going from high rep to lower and back to high again adds a new stimulus so training in cycles like this always gives me a boost.
The muscle being worked and the exercise also play a role;
Going low reps on conventional or trap bar deadlifts 1-5 is pretty much standard.
Romanian deadlifts are more 5- 10 reps.
Leg Press is 10 -15 reps. I never go under 10 as it's a short movement and there wouldn't be enough time under tension on what is essentially a hypertrophy exercise.
Pullups 5 -15 depending on the cycle.
Dumbbell Row 10 -15 reps. Back muscles respond best to heavy weight and high reps. Time under tension is crucial for back.
Barbell Row 5-8 reps. Due to stress on lower back just not worth doing as many reps so go for strength with good form.
Lat Pulldowns 8-12 reps. Control the negative.
Barbell Bench Press 3-5 . Pectorals are fast twitch fibers so use this exercise for strength.
Dumbbell Slight Incline Bench Press 5-10 depending on the cycle I'm in. No point going too high as fast twitch fibers but still good to go heavy enough with added TUT. Great for hypertrophy.
Cable Flies 10-15 go for the pump.
Overhead pressing 8 -12. Any lower doesn't seem to do anything other then cause injury.
Lateral raises 10-15 . Short movement so must do at least 10 reps and always control the negative.
Barbbell Curls 6-12 reps. Never any lower as not worth an injury and you can gain some strength with 6. Higher reps for the pump.
Dumbbell Incline Curls 8-12 never any lower as can cause shoulder issues and if you can go higher add weight. Focus on the squeeze.
Bar Dips 8-15. In theory you should do low reps for triceps as they are fast twitched fibers but my elbows give me hell if I do.
PJR pullovers 8-12. Same reason plus you can focus on TUT with this one.
Rope pushdowns or overhead extension 8-12 reps.
So basically for strength training I start at 5 reps and over the cycle I work it down to 3 or even 2. Deadlifts I'll go down to a single before having a deload then starting back at 5 again. A cycle takes about 6 weeks.
The same style is done for most exercises but in there allotted rep range. For example DB rows I'll start at 15 and work down to 10.
It probably isn't necessary for arms but I don't like using the same weights every week so by doing this you can keep your training interesting. As you get older that becomes important.