I have to say having flown mostly in the US in the last year that comms here can be very sloppy. Americans love abbreviations and shorthands to the point where it can be a slight safety hazard for someone not used to it. I've always said as long as you make yourself understood in a safe way, that's good enough. But I do see the point in sticking to ICAO for some things - it makes it safer. Doesn't mean we all have to say "tree", "fifer" all the time, but at least be accurate when it counts, like altitude changes, clearances and alerts. Not "outta six for three and half" like they do here.