Order flow reading at the open: is it only useful for the first 10 minutes?

[FXS London Scalper]

I spent most of September watching tick-by-tick prints on EURUSD between 07:55 and 08:30 London time, mostly to answer one question for myself: does reading aggression at the open tell me anything after the first burst is over?

My honest notes so far:

• 07:59–08:04. Aggressive prints line up with direction more often than not. If buyers lift the offer repeatedly and price holds above the pre-open high, the first leg usually has follow-through of 6–10 pips.
• 08:05–08:12. Still readable, but the signal gets noisier. Large prints show up on both sides and you start seeing absorption instead of clean pushes.
• After 08:15. For me it becomes almost useless on a retail feed. Liquidity is back to normal, the book refills, and whatever "flow" I think I see is mostly my own bias.

So I treat it like a perishable item. The read is fresh for roughly ten minutes, then I go back to plain structure: prior session high/low, the Asian range and where the first impulse stalled.

One caveat. FX has no central tape, so all of this comes from one broker's feed. A different LP mix might show a different picture, which is exactly why I don't size up on it.

Anyone here using flow tools beyond the first quarter hour and getting something consistent out of them? I'd like to hear what instrument and what feed.