I do 9km (or 5.6 miles) daily. Is it already good enough or should I decrease/increase the amount of roadwork?
Actually, just continue your road work and add in some squats. With the running, you're fine with the distance. Just continually try to run it faster.
I think it’s good to mix up running and sprints, or do intervals (easiest way is run from one telephone pole to the next, jog to the next, run again … or however you want to space it out. In general when I was training people it was 3 miles a day, six days a week with the odd sprinting day mixed in maybe twice a week. If guys liked running farther, I wouldn’t stop them, but if they didn’t do their roadwork I wasn’t going to waste any time on them (and it’s easy to tell when you’re working people out how much they’re cutting corners).
If you are amateur - decrease mileage and add sprints and quick bursts. One day run long 5km-8km run - try running 4km/min. Sprints - 200m, 400m, 800m. F.e. 3 x 800m with 1min pause in between, try to finish every 800m below 3min. You can incorporate quick bursts in sprinting training - 20m, 30m, 40m, 50m, 60m, try to be explosive as possible. After burst, walk back to starting line and then explode again. Try to change running routines and make it more specifical to boxing, that's the point. If you are amateur, fighting 11min, there is no sense to run more than 5km, IMO. Maximum twice a week I would run longer distance, every other day sprints and short lengths, but fast. Hill sprinting is also great - if you have a hill somewhere, use it.
6 miles twice per week and make sure part of your circuit is up a steep hill to build those calves. No need for daily sprints and you will benefit spending more time in the gym on circuits etc.
I like the hill sprinting thing. Reminds me of Walter Payton, one of the greatest running backs in NFL history, who had this hill that he would run up over and over and over to the point of getting beyond exhaustion in the offseason. Apart from the physical benefits, it offers a degree of building mental toughness of pushing yourself to and beyond your limits, and seeing it get easier over time no matter how taxing (anyone who has never run up hills no matter what kind of shape they’re in is going to get their ass kicked for a while until their body adjusts) creates self-confidence. ‘This may be tough, but you’ve been running up that hill and that guy in the other corner hasn’t, so take him somewhere he’s never been and win this last round’ kinda thing. I also thought of another thing we’d do with the guys sometimes to make them get in sprint work and make it fun. We had a parking lot and a road to basically a neighborhood with maybe just a few houses on it (and enough of a sight-line to know if a car was coming from that way so there wasn’t danger of getting someone run over) and we’d end the workout and have guys run patterns and throw football passes to them — basically run as fast as you can and catch the ball. Then come get in back of the line while the next guy goes (groups of maybe three or four). Start with short passes and make them run farther each time. They got the benefits of sprinting but it was also fun and I think good for team-building.