CFD sizing on volatile pairs like $BTCUSD vs. more stable like $EURUSD

Still getting my feet wet with CFDs and trying to figure out how people adjust their sizing for wildly different volatility. On something like $BTCUSD, a small move can be a huge percentage of my account if I'm not careful, but then on $EURUSD, it feels like I'm barely moving the needle with the same proportional size. Do you guys scale position sizes purely based on ATR, or is there a mental adjustment for 'feel' that comes with experience?