I only suggested 5x5/3x8 to lessen the time you are spent in the gym.. but I will also point out 4x12 is hypertrophy territory5x5 or even 3x8 is for strength, providing you are lifting hard.
Put it this way.. 4x12 = 48reps. 5x5 = 25 reps. 3x8 = 24 reps.
Reduce break time to 90 seconds, maybe?
To be fair I haven't noticed a time difference in the gym if I increase my number of reps, I think the reason for this is the actual time spent repping has only increased by a few seconds.
Also, my understanding of rep range was/is as follows, please correct me here and if you have an article you could link me too explaining it I would be very grateful
1 - 2 reps - power
2 - 5 reps - strength
6 - 12 reps - hypertrophy
12+ reps - endurance
Thanks