Fratemate's clock code works well.
Rather than dividing and multiplying all over the place having one simple number to remember. I use 0.284 to get litres of Jet per side... ie I need 500 lbs of fuel x 0.284 = 145 litres a side.
Time on target can be useful as well... 10 seconds late requires a 10 knot increase for (normal cruise speed) seconds (so if normal cruise speed was 240kts, and you were 10 seconds late, you need to do 250kts for 4 minutes to make up the lost time).
Remembering 3x height for profile can be rather hand for night circling as well, not just 60nm out.