It's a grade 2 fault in our driving test if you put the car into neutral at any time without the handbrake on and the car completely stopped, or if you pull in the clutch without changing gears or just before you stop. Depending on how bad the incident was, it can be counted as grade 3, which is instant fail. Getting four grade 2 faults is also an instant fail. It's a big no-no. There is no advantage to it whatsoever anyway, so there's no need to do it. It doesn't prolong engine life (at least not if you do regular maintenance), and uses more fuel. Don't do it kids
IMO, putting the clutch in is almost as bad. What if, for some unknown reason, your brakes fail (probably due to the extra heat they're getting due to no engine braking :razz
. Your only way of slowing down is to dump the clutch, which could easily lock up the drive wheels, especially if the car is RWD, putting you into an spin. Unlikely to happen, and kind of a worst case scenario, but if you had the car in gear with the clutch out, the engine braking would help stop you flying ahead while you realise what the hell just happened.