TOGA ----the prudent Airline professional wouldn't (doesn't ) fly at the limit speeds for each flap setting so holding 180 kts F25 wouldn't be done.....most of us hold about 10 kts margin to allow for speed variations. Limits are limits..
Besides flap limits if you are going to hold 180 kts to 5 nm's then in Asiana's case they needed to lose 43 kts, configure final flap and then spool up. ALL IN ABOUT 2 nm and around 50 seconds. A little de stabilizing I would think and totally unnecessary. The fact the PM was new to the 777 and hand flying a visual approach made it harder to do. No excuses for the TC in the right seat though
