Kimish, that is just amazing. Most women must really have no absolute gauge of lengths to judge the length and girth independently without letting perception fool them. Anyway, your experience seems to indicate that a girth/length ratio of 0.724 or lower is undesirable.
However, I would throw out another way to compute the desired girth for a given length based on the area of the girth. This might be more inline with what a person perceives/feels. To get this ratio it is assumed that the penis is circular, but this assumption should not change the results much. Anyway, just compute the effective diameter from the girth: D_eff = Girth/pi. Then get the effective area: A_eff = pi*D_eff^2 = Girth^2/pi. Finally divide the effective area by the length for the ratio: Ratio = Girth^2/(pi*Length). Thus for a desired ratio and given length you get: Girth = sqrt(Ratio*pi*Length).
For comparison, given a 6.5x5 “ideal”:
7.5 NBP would be 5.37” (vs. 5.77” from above)
8.5 NBP would be 5.72” (vs. 6.53” from above)
These seem like they could be perceived as proportionally thin to me (5.37” is not thin!). Of course I think that the ideal ratio of 6.5x5 would be perceived as a little thin as well (or perhaps “long, but not thick”). Coincidentally, Kimish’s size is almost perfectly inline with this metric - 7.25 NBP results in 5.28” girth for the 6.5x5 ratio.
Personally, I’m 6.5x5.25 and I think it is generally perceived as “kinda thick”; however, using my own ratio as ideal, then for 7.5 NBP you would want a 5.63” girth which is inline with UkranianTitan’s expectations that 5.5” would be “ideal” and 5.75” would be “too thick” for a 7.5” NBP dick.