By no means do I subscribe to the "must spend 10-15%" rule, as every cable decision I make stands alone. I do know I prefer my $100 grover RCA over the stuff thrown in the box, which is OK for testing and such, where I also have some $50 XLR as backups to my $150 APS (bought years ago) every day players.
Oh, and my Quail power cords, at <$30 each are definitely 'good enough', even if I do have 6 of them.
Now my balanced hd800 cable was about $400 (for $1400 phones), of which is $100 cost outright for the Furutech connectors (builder cost), so, yes, a little bling, but matching my Furutech connectors on the amp.
So, to recap, my ACTUAL % is:
Stat: IC ($150), PC (2x $30), HP Cable ($0) = $210
Dynamic: IC ($100), PC (2x $30), HP cable ($400) = $560
Based on the total system: CD ($2300), Amp* ($600), Headphones hd800 or he60 ($1400) - Total $4200
So my current range is 5% on Stats (dedicated HP cable) to ~13% on dynamics. That is where there is zero snake oil, imo. VERY little bling (and none without true functional purpose) but no weakness, either.
*Depends on amp (Liquid Gold or eXStatA: Vulcan or Raven $1500) DIY - which would be 3x if commercial versions.