How do you account for all the background processes and random stuff happening in Windows, do you plug your computer off the internet and kill everything when you game? Because those are often big reason behind 0.1% lows.I always set game graphics options for "0.1% lows". I find the worse case in a game during early game play and tweak from there.
A stutter every 5 to 10s is not playable in my opinion. Variable refresh rate can soften the blow, but how well is up for debate.