By 1964 it was usual for aircraft to sit on the line without their engine covers and no canopy cover. After all, if it could sit on QRA for a month why did it need a cover.
We did put the bungs and blanks in for an A/F servicing, but take them off during a B/F. Thus if we did the usual A/F-B/F service plus snags - which was nearly every flight - the bungs and blanks stayed off. At the end of the week's flying early on Saturday morning, the Back Shift would bung and blank them all for the weekend as each aircraft had its A/F. The next week's Swing Shift came on again at 2359 on Sunday to B/F the morning programme, taking the blanks off those aircraft. The rest would be opened up during their first B/F of the week. Even on QRA the pitot-static blanks were always fitted.
I only ever remember the cockpit cover being used when there was a U/S canopy seal - but it was a hell of a fiddle getting it up there on your own.