What I’ve found to work with my athletes (running the 400) is to run a relatively similar segment of the race in competition warmup that was put in place and executed correctly in practice. Typically early in comps an athlete would do perhaps a 150 or 250 that would be the target opening in the race. Later in the season, as density might rise with decreasing total volume, A shorter opening would be coupled with larger finishing work.
Of course relaxation and moderate emphasis on max sprinting seemed to work for them as well. Recently one female Qmiler went 63.4 (37h/250) to 61.2 (21h/150) within the same training block. However, with a few exceptions, I haven’t worked with many female youth Qmilers so a sample here may not rate significantly.