Viable alternative to the 20%, 30%, 50% calculation

[Inquisitive_Bent]

The 20%, 30%, 50% calculation for recommended VED usage is based on the difference between flaccid length and the erect length (or BPSFL if that is a bit tricky) , so that the 50% mark is half way between the two.
My problem is that my flaccid length is somewhere between 2 and 4 inches.
Assuming that penile tissue stretches about the same amount for everyone. I realise that this could be a big assumption but I would find this helpful.
Can regular users of VED please let me know their erect length and their 50% length. That way I could calculate the 20 and 30% marks.

E.g. is the following about right?
Erect length   50% mark  (inches)
4                       3.3
4.25                    3.5
4.5                     3.8
4.75                    4.0
5                       4.2
5.25                    4.4
5.5                     4.6
5.75                    4.8
6                       5.0

Thanks