No kidding! If you followed those recommended cleaning intervals, you’d spend all your time doing that and never have time to actually make something to serve through your pristine lines! 
The only thing I would add that I hope was obvious is I try to use really hot water, then add oxyclean to it, get it fully disolved then soak/flush with it. Then rinse with hot water.
Since I was broaching a new keg tonight a gunky old line got the treatment. After cleaning a corny I dumped about a gallon of hot water on top of a Tbs of Oxyclean. Pressured up the keg and ran the whole lot through the QD, line and tap then flushed with a gallon of hot water.
Cleaned up real good! Spotless. Thanks!
Are your tape lines more than a year old?
If so, try this.
Clean them as normal, rinse and pour a beer from them.
Now, take out one of the lines, rinse it with hot water and take a sniff… smells like beer huh?