Some people react to things, and doing a whole30 or going 100% at first can help you sort those things out. Things you react to should be eliminated from your diet, while things you don't react to are fine as the non-primal foods you occasionally indulge in.
I would recommend 100% adherence for at least 30 days before you play around with non-primal food again to gauge sensitivities.
I'm not sensitive to dairy, gluten, and I'm at a healthy weight already so if I wanted to do 80/20 I look at it by meals. I got 14 meals in a weak (2x/day). So if I eat out once a week then even if I order a primal meal its highly likely to be prepared with non-primal oils and other crap.... there you go 13/14 meals primal is about 93%. Least thats how I see it.
[QUOTE=Neckhammer;1142001]I would recommend 100% adherence for at least 30 days before you play around with non-primal food again to gauge sensitivities./QUOTE]