What about practicing max effort jumping like how sprinters practice their sprints. If you can do two sessions a day, wouldn't max effort jumping in morning and weightlifting at night be better than combining them into one workout?
There is no universal rule as to how sprinters practice their sprints. Some sprinters have even squatted before sprinting. But that's neither here no there. You are either squatting for potentiation/specific resistance or you are lifting as an accessory.
1) If you are lifting as an accessory to your event (jumping or sprinting) then it should be done after jumping/sprinting so it doesn't interfere with the workout. As to whether it's best to do it in the evening or not depends on the individual. Weightlifting at night will allow for some recovery before lifting which may be desired.... but if you lift at say 8pm then it means that when the athlete gets to the track again at 6am he has had only 10 hours to recovery from lifting AND it might compromise sleep. IMO the ideal schedule would be 6am track, 8am - small protein meal and 30 min rest, 9am weightlifting, 5pm easy tempo/mobility/massage/ice, 10pm sleep. But certainly the most important thing is that you keep the accessory work after track/bounding. Weightlifting as accessory work could involve deadlifts, GHRS, back extensions, volume squatting, etc.
2) If you are lifting for potentiation then lifting can and should be done before the activity. Squatting is not a great potention exercise for sprinters but it can be used for standing vertical jumps. A single heavy deadlift can be used as potention for olympic lifters. Sprinters use resisted running for potenetation/specific resistance. Sprinters don 't perform heavy sled drags after they have done a hard track session, they perform them before because they make the sprinter adapt to a load and actually help mechanics. Same truth for squatting and jumping. I suppose if jumping were a sport training could consist of max singles up to 95%, then vertical jump training, then accessory work.