That's pretty impressive given that they've only just finished filming the latest season, which will hit the BBC later this year - and considering he's already writing other projects such as Taboo, World War Z 2 and Rio.
Anyway, Knight confirmed that he's been busy planning the affairs of the Shelby Company Ltd in an interview with Slate, saying: "I'm about to start writing season six now and if all the wheels fall off, or it goes horribly wrong, there's probably people that will say something [about his writing process].
"But at this moment, it has its own logic and momentum. Right now, it feels as if the characters are just writing themselves."
Season 5 finished filming earlier this month. Credit: BBC
In the same interview, he spoke about how important the whole show is to him. He continued: "Peaky is a very personal thing for me because it's based on stories that I was told as a kid by my parents.
"At the very beginning, I tried to have other writers involved but it just didn't work. There's no writers' room, or any other writer involved. I write everything from beginning to end. Maybe it's just me not being able to let go of something, especially with Peaky. I can't let it go."
There has been quite a bit of speculation about how much more we'll get out of Peaky Blinders. That's down to the fact that Knight has always said that it will run up until World War Two breaks out, but also - presumably - down to the schedules of the cast, many of whom are pretty in-demand right now.
Knight added: I've always had a pretty clear road map of how this works between World War One and World War Two, and it's flexible in that you can get to the destination quicker or slower.
"So in my mind it's probable that we'll get there at the end of series five, it may be series six."
Tommy Shelby. Credit: BBC
"None of us want to short change it, so if we feel that after five there's another one - there's talk of a film and all sorts of things - so we just want to do justice to the people who love it.
"I want it to end with the first air raid siren in Birmingham in the Second World War, so that will be the start of the next chapter in British history. It's that period."
Another who doesn't think that it's time for the show to end is Paul Anderson, who plays Arthur Shelby, the brawn of the Shelby family.
CIllian Murphy will be back for more seasons if needs be. Credit: BBC
Anderson recently told Digital Spy: "I don't know if we can wrap it up in one more season.
"I think we're in '26, '28? And so the Second World War is not for a little while yet. I don't think six episodes is enough to get us there.
"I had this conversation with Cillian [Murphy] about one more season, and we both agreed: listen, if that's it, then yeah, for sure. But it might take two more. I've got a feeling it might take two more."
Let's hope he's right.
Featured Image Credit: BBC