The old pairing of Sherlock Holmes and John Watson left a formula for many detective novels in later generations: a shrewd detective is always accompanied by a relatively dull or honest assistant.

In "A Study in Scarlet", Holmes ruthlessly satirized and ridiculed the famous detectives in the detective novels at that time. The real reason was that Sir Doyle felt that the protagonists in the book at that time solved the case. It's full of too many coincidences, and some of them are even answers obtained through random guessing rather than logical reasoning. This was the reason why he couldn't stand it. Until he wrote the first chapter of "The Sign of Four", when Holmes inferred Watson's life based on his pocket watch, he specifically said to Watson, "I never make guesses. It's very guessing." Bad habit, it is harmful to logical reasoning."

So the biggest feature of the Sherlock Holmes novels created by Sir Doyle is that solving cases relies on reasonable logical reasoning rather than luck. To this end, Sir Doyle also used the argument between Holmes and prosecutor Jones in "The Sign of Four" to argue about what should be used to solve the case. Jones believed that the case of the Bishop's Treasure was solved through good luck. Of course, he could not forget Holmes's theory and how he analyzed the causes and consequences of the case. Holmes believes that based on sound logical reasoning, this is a very simple and clear case. In other cases, Sir Doyle used a lot of scientific data, such as surveying and mapping, calculating dates, deciphering codes, etc., to make the novel's plot bizarre and vivid, but believable. This is why his work endures.

Sir Doyle's works in his later years are more formulaic based on his experience in solving crimes. As for another regret in Sir Doyle's writing style, there is a lack of real novels - his so-called "long novels" are generally fourteen or five chapters.