Actually, I have a different experience.
Some friends of mine are (IMHO) totally irrational with this, listening to their (6yo) child each time she cries.
They have turned themselves into some kind of slaves, and this is absolutely not good in my book.
When my children were toddlers and would cry at night, I would come a couple of time ensuring everything was ok, then I would reassure them but explain I needed to sleep myself, and would not come back until the morning.
This worked really well.
Hell.