"Development cycles" (with the exception of demotions, on occasion) don't influence development, they just report on the development that has happened.
In other words, your prospects are developing even when you don't see increases in the ratings - the various "events" don't "trigger" development.
Get your prospects plenty of playing time, hire good coaches for them, and keep your training budget high if you want the most development you can get. Players with high makeup are also rumored to develop faster than those with low makeup...I can't say that I've observed this.