One thing I have learned recently is people are different.
You cant cookie cutter people. For example if someone hates learning Gemorah, Making them learn 10 hours a day is a recipe for disaster.
You have to properly balance kids. If the bocher for example hates learning , begins to slack off and the Rebbe Slaps him. There is your road to OTD.
If the Girl is dressed properly tzniut but told she cant laugh in public, hears something funny and then laughs and is publically humilated. You have sent someone on the road to OTD.
Privately Im sure you can think of yourself. Speak to your kids try to figure out what borders are acceptable and what are not BEFORE everything collapses.