Clubs have been shying away from signing players in January as they argue that good players are most likely not willing to move midway into the season.
Also, clubs are always reluctant to let their best players leave mid-season.
It is really no surprise that the majority of players who have been transferred in the winter break - with no time to adjust to different surroundings and styles of play - have failed to leave a great impression on their sides, leaving many clubs to concentrate all of their efforts on making summer additions and giving the January window a swerve entirely.
But even without a crucial settling-in period, some January signings have still been able to make a major impression in the Premier League.
Here are three memorable examples from recent years:
Pierre-Emerick Aubameyang - Arsenal
Arsene Wenger's last signing as Arsenal manager has continued to impress during a turbulent time for the Gunners.
Aubameyang arrived from Borussia Dortmund for £56million on the last day of the January transfer window in 2018 and has proved to be money well spent.
A truly elite striker, with excellent pedigree and pace to burn, he demonstrated his quality from the very start. Aubameyang scored on his debut, a 5-1 win over Everton, and ended the season with 10 goals in 13 appearances for the Gunners. He's been a rare bright spot for the club ever since.
Youri Tielemans - Leicester City
The young Belgian midfielder always had plenty of technical quality but was unable to demonstrate it on a consistent basis at a struggling Monaco. He moved to Leicester on loan last January and soon found a place that felt like home.
Tielemans struck up a good understanding with his teammates, particularly the fleet-footed Jamie Vardy, registering three goals and five assists in just 13 games. Brendan Rodgers was understandably desperate to keep him at the King Power Stadium, and a £40million transfer was agreed over the summer despite interest from other clubs.
Jermain Defoe - Sunderland
A year in Toronto proved to be enough for the ageing England striker, who was soon pining for a return to the Premier League. Sunderland swooped in, successfully offloading Jozy Altidore as part of a deal that benefited all parties.
Any lingering concerns that Defoe had lost his edge, and could no longer outwit the country's best defences, were soon dispelled by some vital goals to rescue his new club from the threat of relegation.
He continued to score consistently over the next two years, although Sunderland eventually dropped out of the top flight under David Moyes.