if i can have my pennithworth budgie , i would say a very difficult question,,
my veiw would be management would come first,
,, i,e if you were training the best distance in the world now, then every day, untill july,, this great bird would be finished well b4 the big one [i use this as an exaggerated sample],,
by management i mean , obtaining the best long distance stock, breeding best to best, ridding the offspring rubbish by sensible racing/training, waiting until the birds you think are capable, are mature birds, then at two years old, setting them up for these long distance races, making sure [again by management] that the bird is conditioned to be in top form in july , by this time knowing its best nest condition, having the bird just casting its second flight,, with plenty fuel left in the bird for the job in hand
i do believe there are pigeon fanciers that are better than others at genetics /breeding etc, some farmers seem to be good at this
, but when you see the same fanciers year in, year out, on nat results,, sending very few birds, ,, these are the guys that can fit the jigsaw better than others, they seem to have a" pigeon second sense" ,,, mcormack of wynchburgh was one of this type, never off a nat result in something like 20 odd years,, without sending massive teams, jim sanderson [ a farmer]pathead, winning nantes [600 miles] twice , also second,, is another of many, over the last many years