Headings ending in 5
Yesterday, crusing at FL100, I was instructed to descend to FL70. After acknowledgement I was asked to maintain FL100 and then given a radar heading of 070. The correction was immediate and unambiguous, and presumably came from someone whose mouth didn't speak what their brain was thinking -- happens to us all from time to time.
But it made me recall that a while back there was talk of a convention of using assigned headings ending in 5 where possible to avoid confusion with assigned flight levels, which always end in 0. In yesterday's circumstances it might have sounded an alarm bell in my head if the assigned number had been 075.
What happened to the headings-end-in-5 convention? Not workable in practice?