The slippage of the mantle is not evidence for a change in plan. If parts of the upper pyramid above the bend-line show slippage at those points where parts of the mantle below the bend-line have slipped, it proves that the partial collapse of the pyramid occurred after they had begun work on the upper part. That is, they changed slope before there were any signs of slippage, and this makes it highly possible they changed slope for design reasons.

IIRC, Legon has written about slippage around the bend-line in the NW corner. This supports the contention that the slippage seen in the western passage where the mantle meets the core occurred after they had already changed slope. It may even mean the slippage occurred after the upper part had been completed.

Dorner showed the slope of the Bent lower part was 10:7, breaking the seked rule. With a base of 360 cubits, it would have had a height of 1800 palms or 257c 1p. The core has a width of 300 cubits and a slope of 60 degrees. Now, this can be rendered as either 7:4 or 12:7. If, like the mantle, it broke the seked rule, it would have a slope of 12:7. This would give the core a planned height of 1800 palms, the same as the height of the mantled pyramid. This would have created a constructional impossibility. This could help explain why the change of slope halfway up was planned from the beginning.

There are various other signs that the completed pyramid with two slopes was planned from the beginning.

1. The change of slope occurs 90 cubits up, 90 cubits being exactly one-quarter of the base length.

2. The completed pyramid has a height of 200 cubits.

3. The completed pyramid has two entrances to two different "burial chambers", suggesting that the pyramid was to be thought of as two pyramids in one.