classic strides = something along the lines of
6-10x100m @ mile pace, walk back rest
most often prescribed at the end of easy runs, day before meet, day of meet to develop/maintain speed, warmup, mechanical/form maintenance especially in a phase where you're not doing MD race pace, etc.
modern alternatives:
if you want to build/preserve speed: mile pace, even 800m pace is not NEARLY fast enough. do all out short hills/flys/<60m sprints
if you specifically care about mechanics at a mid-distance pace: 100m is not long enough. you can warm up with ~100m, but you get a lot more payoff going for 20-30 seconds, which for a varsity hs athlete will be quite a bit longer than 100m
these are more load than classic strides. programs exist which do classic strides literally every day and the kids don't get hurt. you would not be able to do these every day. i would argue though if you have 1 day including top speed, 1 day including middle distance mechanics in a week, that is far more effective than mile pace strides every day.
genius coaches of LRC i would love to know ur thots