What is the magic number?
Seamus McEnaney was the latest manager to ponder that on Saturday night as he picked at the carcass of a draw with Dublin that, by any rational analysis, should instead have been a Monaghan victory.
Maybe it was just 'Banty' deflecting from the situation in which his team led by nine points in the 60th minute and still six in the 70th but contrived not to win.
But his biggest beef afterwards - or at least the one that he most swiftly admitted to - was Monaghan's failure to convert their near complete superiority in the first half into a deeper scoring haul.
"The most disappointing thing about it was the first half," he stressed.
"We only had a 53 per cent shot ratio to scores and that was the most disappointing thing."
It was true. Monaghan played with a zip Dublin couldn't match in that first period.
But they still failed to hit the 20-point mark, the scoring tally that has become accepted as the minimum requirement for beating Dublin in the era of sky blue supremacy.
"We felt coming up here tonight that it would potentially be 2-15 to win the game against Dublin," McEnaney admitted.
"You have to be at that scoring level to compete with Dublin and to beat them."
Monaghan finished with 1-15.
That number would have good enough to beat Dublin in just 24 of Jim Gavin's 107 games as manager.
Even the mythical 20-point figure, generally seen as the golden number required to topple the Dubs, is not an exact calculation.
Of those 107 league and championship matches overseen by Gavin as manager, Dublin scored at least 20 points in 58.
So between 2013 and '19, 20 points would not have been sufficient to beat Dublin in 54 per cent of the games they played.
Different teams and players with genuine designs on beating Dublin have different theories.
"Against Dublin, I've always had this 20-point marker in my head," said Andy Moran in 2018, then reigning Footballer of the Year.
"If you get to 20 points you think you have a chance to beat them."
Moran didn't conjure that figure from thin air.
Mayo scored 1-16 in the previous year's All-Ireland final, a point short of that mark and agonisingly, one less than Dublin in arguably the greatest final of the decade.
The same goes for Kerry.
Only a minimal improvement on the 0-19 they scored on September 1 last year would have been enough to crown them All-Ireland champions.
So in both of those cases, 20 points was an astute calculation, albeit one neither team managed to achieve.
But taking Gavin's wildly successful stint as manager as a revealing sample size, the uncomfortable truth for Dublin's rivals is that there is no hard and fast rule, no golden number.
Simply meeting a scoring target is no guarantee of success.
True, the 3-14 (23 points) Donegal managed in the 2014 All-Ireland semi-final was the highest score Dublin conceded across Gavin's spell in charge and led to their only defeat in seven years of championship football.
But it was only minimally higher than the 2-16 (22 points) Roscommon got in Croke Park in the last round of 'Super 8s' fixtures in 2018 - and they wound up losing by 14 points.
In total, 11 teams managed to hit the unofficial 20-point target against Dublin in those 107 games.
Just three of those came away with victories; Donegal in '14, Kerry in the 2017 League final (0-20) and Kerry again last year in the League in Tralee (2-18).
As it happened, one team met that mark in each summer over which Gavin presided.
But failure to handle Dublin defensively cost every one bar Jim McGuinness's Donegal.
Kerry's 3-11 (20 points) in the epic '13 semi-final was good enough only for a seven-point defeat.
In '15, Fermanagh managed 2-15 (21) in their All-Ireland quarter-final but lost by eight.
A year later in another instant-classic semi-final, Kerry scored 2-14 (20) in vain while Kildare's 1-17 (20) in the 2017 Leinster SFC final is the only time Dublin conceded 20 points or more in provincial action in that time.
The Lilies still lost by nine points.
Roscommon's 2-16 (22) in '18 is the highest tally any team scored against Gavin's Dublin without winning and the second largest over the expanse of Gavin's time in charge.
The last team to meet the 20 mark against him were Cork (1-17) in last year's 'Super 8s' opening night en route to a 13-point hammering.
All of which indicates that the accepted wisdom of 20 points is probably a low-ball estimate.
"Probably 1-20, 2-20 you'd need to be looking at," was Michael Murphy's verdict when asked last year.
"I do believe that you do need to rack up a score against Dublin and it's probably one of the things that teams haven't been able to do over the last number of years because they were so interested in how to stop Dublin.
"So I think that's always the big challenge, racking up a big score to actually match their score."
True, but in the 11 matches Dublin lost in that time (10 in the league, one in the championship) only four were achieved from the platform of scoring a tally the equivalent of or greater than 20 points.
A strong defensive display is at least equally important to the collating of a significant scoring total.
So what is the magic number? The figures show that in 107 games under Gavin, Dublin scored 161-1908 or 21.4 points game.
So the notional figure of 20 points is significantly under Dublin's average score.
Worse for those intent on toppling the All-Ireland champions from their perennial spot on the podium on the Hogan Stand is that in 48 championship games between 2013 and '19, they scored 94-886, an average of 24.33.
And the last team to hit that mark that against Dublin in championship football was Kerry in 2009.