"long developed" is a correct and usable phrase in written English.
It can be used to describe something that has been developed over a long period of time or has undergone extensive development. Example: The city's infrastructure is long developed, with well-maintained roads and modern public transportation systems.
The Japanese, who had long developed smaller and more fuel-efficient cars, were eventually welcomed in Britain and their experience helped to resurrect UK manufacturing.
The malaria parasite had long developed ways to fend off one type of drug, chloroquine, and doctors feared it would increasingly resist artemisinin, a newer treatment.
A therapist at Centerstone Mental Health, Dr Long developed therapy programs related to her love of horses, dogs and helping children.
Holden, an innovative character, had long developed the habit of crunching up the remnants of his salt'n'vinegar crisps into a rough powder and dipping a pickled egg into them.
Yesterday, we crowded around Bela Karolyi, who has long developed Olympic gymnastics talent for the United States, and he spoke of how proud he was of the team, of how this was the greatest competition he had seen in the last 15 years.
As a company, RapidMiner long developed its tools in an open-source fashion.
Julie Bell, the brand's executive vice president of Global Marketing, explains why it's taken so long, "Developing deeper foundation shades can be challenging.
"Since we're in the military, we don't have time for long, developing friendships," said Cathy Ekman, a friend of the bride and a military wife.
Before long, Natalie Ogarev developed feelings for Herzen.
Mr. Washington maintains that Mr. Roney long ago developed "his own big, dark sound".
Before long, she developed a precocious childhood fascination with the R & B masters Ray Charles and Jackie Wilson.
