The coaches would like the market to close for all the leagues on the same day, but this request is nearly impossible to fulfill because Eastern clubs often expect to know if they are qualified for the Champions League or the Europa League before they decide to invest.
Uefa are set to introduce a third European club competition alongside the Champions League and Europa League.
As well as the future of Europe's club competitions, Agnelli told ECA members that UEFA's revised Financial Fair Play rules "will be even more effective than the ones we had in place which delivered astonishing results" - this being a reference to the dramatic reduction in club debt since the cost-control measures were introduced in 2011.
The new competition will bring the overall number of clubs involved in European football to 96.
The plan for three competitions would create 16 new places and take 16 teams from the current 48-team Europa League group stage.
Nawaz Sharif's wife Kulsoom Nawaz dies in London
Former three-time Pakistan prime minister Nawaz Sharif's wife, Kulsoom Nawaz, breathed her last at a London hospital on Tuesday. This was reportedly the last time Nawaz Sharif had spoken to his wife. "In a personal capacity, she was a very loving woman".
The decision still subject to ratification by the UEFA executive committee is said to be a strategy to further boost the body's revenue as well as provide a competition for smaller teams asides the Europa League.
Agnelli, who is also chairman of Italian champions Juventus, said: "A detailed assessment of the existing global match calendar is required prior to presenting a new model post-2024". Others claim the football calendar is already busy enough.
Details on how the new UEFA competition will work remain uncertain but it will not be a straight replacement for the Cup Winners' Cup, which was discontinued in 1999.
When Lazio beat Mallorca 2-1 at Villa Park in Birmingham, England, in May 1999, the Roman side became the 39th and last winners of the European Cup Winners' Cup before the competition was abolished.