It is a difficult one to understand for the millions whose working life consists of shifts of eight or more hours at a time for the best part of 250 days a year, but there are those in other walks of life who only really need to deliver for an hour and a half at a time on a maximum of 60 - and often much nearer 40 - days.

GettyImagesRobin van Persie has scored 37 goals in all competitions this season

Welcome to the world of the professional footballer. Richly remunerated, often idolised, invariably indulged; it sounds a dream existence. The least they could do in return, it might be assumed, is to perform regularly at a high standard when required.

Yet assess the current season and it is notable how few players have sustained excellence over the whole campaign. Robin van Persie deserves all the individual accolades for many reasons but foremost among them is his dependability. While there has been a slight drop-off in the Dutchman's displays of late - he has only scored once in his last six games - the Arsenal captain's prolonged purple patch makes him stand out.

Consider the other candidates for the PFA Player of the Year award: Wayne Rooney, though prolific, has delivered goals more consistently than performances; Joe Hart, as can happen to goalkeepers, has gone untested for parts of the year; Scott Parker enjoyed a better 2011 than 2012; and David Silva's nomination is on the basis of an outstanding first three months of the season, rather than the subsequent spell. Sergio Aguero is the contender who has come closest to emulating Van Persie.

Not for the first time, footballers' judgments can be faulted. Clint Dempsey, who has scored regularly from August to April, is especially unlucky not to earn official recognition. Goalkeepers and defenders, whether Tim Krul, Michel Vorm, Vincent Kompany or Fabricio Coloccini, can claim consistency, too, but by the nature of their position, they are less subject to the vagaries of form. Inspiration is not a prerequisite for them to excel and given the physical, technical and mental demands, it is utterly unrealistic to expect, say, Steven Gerrard to be at his barnstorming best game in, game out.

But look at who the outstanding individuals of recent weeks have been and how they fared earlier in the season: Tomas Rosicky, for instance, has been superb for the past two months but was anonymous beforehand; Papiss Demba Cisse, Nikica Jelavic and Gylfi Sigurdsson were all signed in January; even City's former misfit Carlos Tevez has impressed of late, albeit over a couple of games.

Think of the reasons for a terrific three months in which Manchester United have only dropped five points: Michael Carrick and Antonio Valencia, whose fine form began in November; Rio Ferdinand, Jonny Evans and David de Gea, who improved from January; and Paul Scholes, whose campaign did not commence until his New Year return from retirement (and, great player as the 37 year old is, ten league starts is far too few for him to be deemed the Footballer of the Year).

And hark back to the start of the season and those who touched the heights then: Silva and his Manchester City team-mates, of whom Yaya Toure and Micah Richards have almost maintained their levels, and Edin Dzeko, who has veered from terrific to terrible; Daniel Sturridge, now only on the bench for Chelsea; Jose Enrique, left out by Liverpool for the FA Cup semi-final win over Everton; Newcastle striker Demba Ba, who has only scored twice in 2012.

Ba provided the platform for the unexpected transformation on Tyneside, but now Newcastle are being propelled towards the Champions League by Hatem Ben Arfa, either injured or a replacement in the first half of the season, and Cisse, a Freiburg forward then. It illustrates that teams can be best served if, whether by intent or design, different players hit form at various stages of the season, although it may take a managerial mastermind to plan a campaign with such meticulousness and accuracy that he had 11 footballers at the top of their game at every point. More pertinently, perhaps, Manchester United have long aimed to be at their most potent in the run-in.

Chelsea, too, seem to have their competitive juices stirred by the business end of the campaign, even if their renaissance is attributable to the dismissal of Andre Villas-Boas. But their FA Cup victims are the antithesis of Newcastle: Tottenham highlight the problems of a team all peaking at the same time - not that, when they stylishly and speedily eviscerated opponents in the autumn, it appeared a flaw - as now they are in a collective slump. Ledley King, Luka Modric, Emmanuel Adebayor and Rafael van der Vaart's displays have deteriorated more dramatically than the ever willing Parker's.

GettyImagesRoberto Martinez: Eager to become Reds boss

Those with lofty aspirations require consistency; those at the other end of the table find it less important. Indeed Wigan, whose side are reaching individual and collective heights, could render their early-season run of eight successive defeats irrelevant with a brilliant conclusion to the campaign.

That said, the pick of Roberto Martinez's bunch before Christmas was Mohamed Diame, now on the bench. West Bromwich Albion have the same scenario with Shane Long. They are not alone. That plenty of players only really flourished for two or three months highlights how remarkable Van Persie's season has been.

While there can be sepia-tinted calls for unchanged teams and established starting line-ups, it also highlights how significant the deployment of a squad is and renders the manager more important. Ultimately, he has to realise September's strongest 11 may not be the men for March and he needs to perm the right players for the appropriate occasions. Because for many, it is not a 60-game season; it is not even about starting 40 matches. Play genuinely well 20 times and many have done their job for the year.