I never did think about this, till you brought it up.
But isn't such theory more adequately applicable in a non-wildly-fluctuating market?
Cause for all I know... BTC might go down 1% for weeks, before actually heading to the resistance.
I'm guessing by resistance you actually mean support since you're talking about price going down. And by all means no, R:R-trading is especially important in cryptos since the volatility is so great compared to traditional markets. I'd rather lose 1% in a major dump than lets say 7% by having a good R:R-setup.
And lets take an example here, you said "BTC might go down for weeks".
You take long right now and BTC goes down for 4 weeks straight 1% per week. At the end of this week your stop-loss activates and you lost 1%. If you wouldn't have had that good of a R:R-setup your loss would be 4% without setting up your stop-loss.
Best R:R-setups are often found at supports, you open long directly at support with good R:R, and your stop-loss being set below the support line. This would give you the chance to either lose 1% at MAX or gain 3% judgeing by the current price action were having between 6561 and 6754.