Just to cover one 'extra' little trick of scanning...
Sometimes you do want that input in the radio, as some agencies (Federal groups were famous for doing this) would go to the input, with the CTCSS that would activate the repeater turned off, so it wouldn't be repeated, as a 'secret' simplex channel. In other cases, they'd go simplex on the input with CTCSS still on, for scenes where the inside a building unit couldn't hit the repeater, but could talk to the mobiles outside, and the outside units wanted to be able to repeat what the inside unit said on the repeater without having to change channels.