Sleep training question, TCB/pop in method.

Okay so question about the TCB/pop in method. When you do your pop ins do you wait until baby is done crying to leave or do you just pop in, pat them/reassure them and then leave?

Also how long do you let them cry before you intervene? I can’t imagine letting a baby cry for 2 hours.

Oh! and what if they are crying ridiculously hard, what do you do then?

NO JUDGEMENT PLEASE.