That's true, the points are fixed. But the amount of points required for allocation is variable.
I just looked up the terms and conditions of Wüstenblau again.
I was a bit imprecise above.
A prerequisite for an allocation is that the minimum savings period, the minimum savings amount (30/40/50%), and the minimum valuation number are met. That was still in my head.
In addition, there is a target valuation number that you must have at least in order to actually receive money if the available capital of the building society is not sufficient for everyone. Only then is an allocation actually made.
In general, you cannot say that a building savings contract is bad, otherwise this model would not have worked for decades. From a financial perspective, it is a bet on (strongly) rising interest rates.
Due to long fixed interest periods, there are now alternatives in the annuity sector to building savings contracts that are designed for (interest rate security). Adding to this are savers with old contracts with attractive credit interest rates. That obviously does not make it easy for the building societies. You just have to know what is important to you in financing.