Those 100-300 Swings per Day Challenges - Is it overtraining?

Not sure if those are more of a gimmick but I see those do 100-300 swings per day for 30 days initiatives a lot.

However I read that one shouldn’t do HIIT exercises everyday and should be about 3x a week to allow for healing. Supposedly too much HIIT could have diminishing returns and lead to injury, cortisol spikes, and hormonal issues.

When I go an extended period without using kettlebell, I am often sore for 3+ days haha.