Why is the average number of suspects three or more in Detective Conan? I'm curious as to why in almost every Detective Conan case there are always around three suspects? Even when there are cases with many suspects, Conan always narrows it down to three or four suspects. When there is a case involving a serial killer there are at least three suspects at the end.

Is there any explanation from Aoyama Gosho about this?
Three is a number that would make the story go more smoothly. If there were only 2 suspects, the evidence would continuously weigh one one another, making the case go for 5 chapters compared to the usual three. If there are four, or more than such, it would be like watching longer replays of the 50 million suspects case, but these are fillers with no specific information that is important to the timeline, so they should not go longer than 3 chapters.