The constant hiring and firing of managers is "severely damaging" to English football, according to League Managers Association (LMA) chief executive Richard Bevan.
A Press Association Sport study has found Premier League and Football League clubs used an average of 12 managers between October 1997 and Nov. 1 this year, with Notts County and Crystal Palace each employing more than 20.
Arsene Wenger has managed Arsenal throughout the study period, with Morecambe using only three managers and Manchester United four, but Bevan says clubs are too quick to pull the trigger.
He told Press Association Sport: "The LMA continues to view the hire-and-fire culture, endemic in football, as severely damaging to the game. It causes a series of negative consequences and we will continue to be vocal on this issue.
"Firstly, there is a misconception that changing a manager consistently leads to an improvement in results. Whilst it is often well publicised when an under-performing side regain form under new management, this is rarely sustained over long periods and quite often results revert to type within a few games.
"Consistently dismissing managers can create an environment of instability within the club. Inevitably, constant changes to the management and coaching staff leads to instability within the playing staff and can have a knock-on effect throughout the organisation. This also breeds a culture of uncertainty within the incoming staff."
Arsenal have had just one manager since October 1, 1997, but which of the 92 clubs in the Premier League and Football League have hired the most in the last 20 years? #PremierLeague #EFL pic.twitter.com/t8dMrDfBih
— PA Dugout (@PAdugout) November 13, 2017
The study featured managerial tenures as short as Billy McKinlay's nine days at Watford in 2014 and Bevan, without referencing specific cases, said: "The direct impact on the manager, the coaches and their families cannot be underestimated.
"These individuals are dedicated to football and treating the talent within our game in such a disposable way will have longer-term consequences, including making the profession less attractive."
The link between managerial stability and footballing success is backed up by the study. Wenger celebrated 20 years at Arsenal in 2016, while Sir Alex Ferguson's 26-year reign at Manchester United, which ended in 2013, occupied the bulk of the study period.
At the other end of the scale, Notts County have cycled through a remarkable 23 managers in 20 years while Crystal Palace's swift sacking of Frank de Boer was not out of character -- they are just two behind County and are the only other team to surpass 20 managers.
Press Association Sport put together a "success index," with one point added for a trophy or a promotion and one subtracted for a relegation. The 10 clubs with fewest managers combined for an index score of 38 while the 13 teams (10 and ties) with most managers totalled just four.
Just 10 teams in Premier League and Football League have had the same manager in place for four years or more. But, who has had the shortest reign since the beginning of our study between October 1, 1997 and November 1, 2017? #PremierLeague #EFL pic.twitter.com/K7SjVEyoRP
— PA Dugout (@PAdugout) November 13, 2017
The study found that:
:: The average club used almost 12 managers (11.93) in the study period.
:: Morecambe, with just three managers in 20 years, split Arsenal and United (four) in making the fewest permanent appointments.
:: Accrington and Everton (five), Crewe and Ipswich (six) and Bournemouth, Burnley and Burton (seven) round out the 10 clubs with fewest bosses, although Everton had sacked their fifth appointment -- Ronald Koeman -- and had not appointed a permanent successor by the end of the study period.
:: United scooped 19 major trophies, 16 of them under Ferguson including nine Premier League crowns. Arsenal added three league titles and seven FA Cups while Crewe won the 2013 EFL Trophy.
:: United, Arsenal and Everton spent the entire study period in the top flight, with the other seven clubs with the fewest permanent appointments combining for 17 promotions and nine relegations.
:: Bournemouth climbed from League Two to the Premier League and Burton from the Northern Premier League to the Championship, while the relegations were shared among the clubs with six or seven managers (Crewe four, Bournemouth two, Burnley two, Ipswich one).
:: County's hiring and firing has not helped them progress -- over the 20 years they have had two promotions and three relegations.
:: Palace have twice dropped out of the Premier League only to return on both occasions. De Boer's sacking followed a winless start this season which leaves them in another survival fight.
:: Portsmouth won the FA Cup under Harry Redknapp, who accounts for two of their 19 managerial appointments, but they also crashed from the Premier League to League Two before bouncing back to the third tier last season.
:: Swindon and Oldham have each used 18 managers, with 17 apiece for Leeds, Nottingham Forest, Southampton and Swansea and 16 for Barnsley, Brentford, Leicester and QPR.
:: Six of Leeds' 17 appointments were made under controversial former majority shareholder Massimo Cellino, nicknamed "the manager eater," in a period spanning June 2014 to June 2016, when the last Cellino appointment -- Garry Monk -- was announced.
:: The 13 clubs making the most permanent appointments have combined for seven trophies, 27 promotions and 30 relegations. Seven are in a lower division now than at the start of the 1997-98 season, with only Brentford and Swansea progressing to a higher division.
:: Leicester, the shock 2016 Premier League champions who also won the League Cup in 2000, went through three relegations and three promotions.
:: Swansea climbed from the fourth tier to the Premier League, adding the 2013 League Cup and an EFL Trophy, and had only one relegation in 2001.