Ok I will tell you what I used last year to fill in my Yukon yard during renovation.
I alternate every 15 days I put down 1 pound nitrogen. During active growing season
1st app I use my 22-0-4 which is 50% slow release and 50% fast
15 days later I use Amonium Sulfate at the same rate.
This year , All spring dead spot Grew in quickly and I had to mow the lawn an ungodly amount to maintain at 1/2 inch. Every other day. I did it the entire year last year during my renovation.
But yeah I can't mow that much this year because I don't have the time. So I have cut back to 1pound N. Per month. I think @J_nick
went over the 1pound rule with his renovation as well during grow in.
It's important not to push nitrogen for warm season lawns during the fall. I think it promotes snow mold. And prevents carbohydrate storage for the winter.
I'm not sure how much is to much. That's a good question for @thegrassfactor
I think Ive seen him apply more than 1 pound N per month as well. I know he "Hammers It!"