I remember hours of high power engine runs on Tristars
If the RB211 was test bed run and serviceable, even back in the 70s it only needed a leak check and GI/FI and gen disconnect.
But where I worked, the engines were not test bed run (we didn't have one), so we did Test 1 to 17 incl. With no problems we could do it in 45mins. It was Test 4 and 5 that took the time as you were bedding in the abradable liners! But then we got lots of practice! 13 Tristars, HPT blade hard life 1200cycles.