Hill sprints are excellent, you’ve got to realize how hard that is on the body though, all that vertical work is brutal. I would put in a much longer rest that just 1:1 on hill sprints as well, I would say more like 1:5 or so. I’ve done hill sprints for 300 meters where after the second set, all I could do was roll around on the ground until my legs stopped burning, I was basically useless after that and for several days after ward.
Here is another good one with some standardization. Either go to a basketball court or measure out 50 feet, a regulation basketball court is 50 feet wide. Start at one sideline and start your watch sprinting to the other line touching it with your foot, turning around and sprinting back to the other line. Each time you touch a line, count it; do it 16 times. This is called a 16 in :60 if your in good shape you should be able to repeatedly do this in under :60 seconds.