i think it depends on many things , you can send a fit cock for 3 or 4 weeks and he isnt far off then ,due to feeding,or weather conditions or ..... many other individual factors ,he reaches his peak. have had them card over 5 weeks . jmo.
ive used it and missed a season without it , i think what benefits there are effect the health not the performance of the pigeon . if they are looking for it ,then they must crave it .i think in many ways the birds know better than the fancier what they need or want .