The phrase "a lengthy set of" is correct and usable in written English.
It can be used when referring to a collection or group of items, tasks, or information that is extensive in nature.
Example: "The report included a lengthy set of recommendations for improving the company's performance."
Alternatives: "an extensive collection of" or "a comprehensive array of".
Shortly after Tugendhat issued the gagging order a lengthy set of allegations appeared online.
It was the latest in a lengthy set of complications for an already complicated show.
Among these documents is a lengthy set of transcripts from a canon law trial in the 1220s.
"The choice between those two alternatives is yours and yours alone to make," said Judge George O'Toole, beginning a lengthy set of instructions to the jury.
The committee, fiercely protective of its power of the purse, approved a lengthy set of recommendations that accused the administration of eroding a fundamental tenet of the Constitution's separation of powers.
Vending machines in high schools could offer only products meeting a lengthy set of criteria, such as "nonnutritive-sweetened, noncaffeinated, noncarbonated, nonfortified beverages that contain less than five calories per serving".
One episode required Merton to perform a lengthy set piece of storytelling, recounting the history of the Hashshashins to an assembled throng.
In a leaked picture on social media, it was revealed that the models were given a rather lengthy set of instructions for their time on the stage which included 'no eye contact'dodo not act cool'nono sharp movements.' As for the collection it was much the same as previous season - bodysuits, puffa jackets, leggings - with the addition of a splash of colour.
Yet, apart from being computationally tedious, training-based methods depend largely on the test data, and unless a very lengthy set of training data is used, their performance may not be reliable.
The first part is a sort of road movie; the second, a lengthy set piece at the plantation, and largely within the mansion.
It's a dry and lengthy set of figures, but also a revealing one.
