losthog, in his specific question tonnage is NOT his friend. He is asking specifically about working up to a 5 or 6RM. So I assume that he is asking about which of these 2 strategies will help get to the higher 5 or 6RM in the workout. Not necessarily which approach will lead to the greatest gains.
In that case, the 1/6 contrast would be best since it will minimize fatigue for the sets of 5 or 6, while amping up the nervous system even more.
The key though is to use the singles to potentiate the sets of 5-6, not to improve your 1RM strength.
This means that the singles are heavy enough to help neurologicaly and psychologically but not so heavy that they drain the nervous system. So the weight used for the singles doesn’t increase.
It could look something like this:
1 x 1 @ 90% / 1 x 6 @ 77.5% / 1 x 1 @ 90% / 1 x 6 @ 80% / 1 x 1 @ 90% / 1 x 6 @ 82.5.5 / 1 x 1 @ 90% / 1 x 6 @ 85%
Percentages being only for illustration purposes