Hey chris :)
To the next level it's better do maximum sets and reps that you marked or not ?
The reason there's for example 4-6 sets and 6-12 reps, is because some people can do 4 sets of 6 reps (minimum, which still counts, you can still go to the next level), or some can do 6 sets of 12 reps. It is better to try max sets & reps because you push yourself kinda beyond your limits, but you 'pass' the level just with minimum 'requirements' or in this case sets & reps.. Hope that helped
Ok thanks for your answer :)