Nope my friend...not correct. let me explain.
This actually is a 2 bar rule but somewhere someone started calling it 4 bar rule and some say 2 bars...some 4 bars...same rule.
The rule is NOT for fresh entry but it is for stoploss for existing position. We will take example for long position.Suppose you have a sequence of 4 consecutive bars with HH ,HL ,steep rise with a WRB possibly,no pivot lows in the viccinity,then on completion og 4 th bar, you can shift your SAR for your long position to the low of a bar 2 bars ago ie 2nd bar low-f. Once 5th bar makes a new high (from 5th bar onwards,you need not wait for bar to close )you can shift SAR to low of 2 bars back ie low of 3rd bar -f .....so on so forth. Mirror image for short position
Best Wishes,
Smart_trade