What's the acceptable wait time for payment? IMO, its 30 days

When you go to a restaurant you pay before you leave right.
Why do we have to wait 30,60 ,90 days or more. Personally iI think 30 days is enough time to process paperwork. I pay my suppliers in 30. As stated above we are not bankers. Stay on top of it. After 15 days check in and make sure they have recieved your bill. 1/2 the buisness is working the other 1/2 is getting paid. At what point is it considered steeling. You decide.