if you're warmed up already you can go strainght to rep range you want no matter what it is safely.
The thing is pregression why lift a weight you're already capable and used to in the rep range yu want to acomplish?
I want to work in power weeks in the 4-6 rep range so I pick up the weights that allow me to to stay in the range and always trying to beat them.
Now if you don't have a rep range established or if you go trough various ranges in the same set what want to do is always try to progress in reps or weight, not just lift 3/4 sets like they are warm ups to the "heaviest one"... every set counts and it should lead to progression in weights or reps.
@Pickle : they felt easy, done in control motion slow negative... really nice.