Just to be clear, for those who don’t know, a lunging whip, or even a training whip, or a short crop, should never, ever be used to hit a horse.
That is not their purpose.
A stallion drives its herd from behind , and impulsion in a horse comes from the back legs, so the theory of long training whips is that you mimic and encourage forward impulsion when mounted, or from the ground, by applying a feather light touch on the flank, as obviously when you are mounted you can’t use your arms to extend backwards far enough to do that, so the whip is an extension of your arm.
Occasionally a crop can be used to steer but never hit. If you have to hit a horse to
get it to move, or speed up, you need to work on your riding skills or horse training.
Hitting should never be used - if you are frustrated you walk away - hitting with whips or no whips should not form part of any standard training regime.
Similarly, spurs are only to be used by experienced, balanced riders with an independent seat. Nowadays they are rounded and blunt and are used to touch the horse lightly on the flank in a tiny area, rather than using a squeeze of the heels. But a good rider with a properly trained horse should be able to use their seat and weight distribution to stop and start and increase and decrease speed. Ironically, correct dressage training helps you do this!