How to mark a session high without redrawing every five minutes
The session high is a fact that can change, but your sheet should not look like a palimpsest. Pencil, patience, and two closes.
Most ruined session sheets share a look: a forest of erased lines at the top of the page where the writer kept promoting a new high. The high did change. The problem was the ritual of treating each new tick as a reason to rebuild the whole morning.
We use a blunt rule in the room. The session high is the highest print so far. You may mark it in pencil as soon as a candle closes with that print. You may not ink it, and you may not draw a horizontal across the whole sheet, until two later 15-minute candles have closed without taking it out. If they do take it out, the old pencil mark is simply wrong, and you move it. That is not indecision. That is the high still being made.
Why two closes? One close can be a spike that the next bar immediately continues. Two closes that fail to go through give you something you can talk about: a candidate extreme. It is still only a candidate. A later hour can take it out, especially if New York joins. The point is to stop the sheet from being redrawn on every tick while the bar is still open.
The same rule applies to the session low. People are often quicker to lock in a low after a hammer, because the shape is comforting. Comfort is not a method. If the next bar walks down through the hammer's low, the hammer was a pause. Your sheet should show that without shame.
If you only have a screen and no paper, the method still works: a sticky note with the candidate high and the time it printed, and a rule that you do not promote a 'break' until two closes exist. The canvas on the wall in Cross Inn is only a large version of that discipline.