I've done a lot of supply, obviously I see the worst of some schools.
A lot can be said for a clear and universally applied policy, but policies that you cannot abide by - that leads to disruption being got away with.
My favorite school discipline wise had 2 different detentions, one for work not completed which was done with the subject teacher at the subject teacher's convenience and a discipline one.
Each lesson a#was a clean slate, first misbehaviour the child's name went on the board, second the name was ticked, a third and the child went to detention that day for 45 mins of writing, copying out of a book ii good handwriting.
The detention was all in one room and staff were on a rota.
So if you had departmental meeting you could still give detention.
At another school detention has to be taken by the teacher issuing it, so if you have a meeting or anything else you cannot give a detention.
I have been known to spend a free period calling parents, not of the disruptive children but of the ones trying their best because I don't always get time in class to thank them.
I have been told not to thank children but I generally do at the end of the lesson. The majority are putting up with the disruption and they deserve thanks. Also if I'm on a daily supply I appologise for not getting their names right.
Another thing is back up, if a teacher issues a detention it should be a detention, not go whining to another teacher who cancels it.
Oh and being seen to be fair. At one school I was only at for a day I told the class to sit in their seating plan from their usual teacher, asked them to make sure they were and just before I took the register checked they were in the seating plan.
I know they are not, I'm supply, they don't know I have a copy of the seating plan, and I might not know everyone's name but I know that the first person on the register should be sitting at the back so when I called his name and he was sat right in front of me I could give him a detention and the rest of the class got 1 min to sit in 'their' seats.