I used to mark a 30-minute London open range on the majors. Too often the "break" was just the range finishing its own formation, and I was chasing the end of the box rather than a real expansion. Switching some pairs to a 15-minute box on M5 gave earlier structure — and also more failed breaks that needed a fade rule.
Current compromise: EURUSD and GBPUSD get 15 minutes if Asia was compressed; 30 minutes if Asia was already lively and I still insist on ORB. Stop placement scales with the box so I am not risking a 30-minute stop on a 15-minute idea. I will not mix windows mid-trade or change the box because the first break looked "almost".
I log window length as a field now. Without that tag, you cannot tell whether the strategy or the clock is failing.
- 15 or 30 for your London ORB — and on which pairs?
- Do you ever use a hybrid (15 for entry trigger, 30 for invalidation)?
