Well, it’s like wave loading.
Plan for the 2nd wave to be close to an all-out effort on the set of 6 (around 82% for most people).
Understand that each wave is heavier than the preceding one. When you complete a wave, you start the next one, even if you know you won’t likely hit all 6 reps.
When you can’t complete the 6 reps on a set, stop the exercise.
If you successfully complete 2 waves but fail to complete the 3rd one (you get 4 or 5 reps) you use the same weights for the next workout.
For example if you get:
1 x 1 @ 270 / 1 x 6 @ 235, 1 x 1 @ 270 / 1 x 6 @ 245, 1 x 1 @ 270 / 1 x 4 @ 255
You do the same thing the next week.
If you complete 3 waves, the next workout you start the 1st wave with the weight used in the 2nd wave the preceding week and add around 10lbs on the sets of 1. For example let’s say that you do…
1 x 1 @ 270 / 1 x 6 @ 235, 1 x 1 @ 270 / 1 x 6 @ 245, 1 x 1 @ 270 / 1 x 6 @ 255, 1 x 1 @ 270 / 1 x 4 @ 265
You would do…
1 x 1 @ 280 / 1 x 6 @ 245, 1 x 1 @ 280 / 1 x 6 @ 255, 1 x 1 @ 280 / 1 x 6 @ 265, 1 x 1 @ 280 / 1 x 4 (or 5, 6 depending on how much you get) x 275
If you complete 4 waves you likely picked a weight that was too light, but if that happens the next week you do your 1st set with the weight you use for your 3rd wave and add 20-30lbs to the sets of 1