One thing I've noted in FX is that A-levels of the preceding session often act as interesting levels later on -- I wouldn't say S/R levels in the TA sense per se.
For example look at my chart here:
The time on this chart is GMT, the OR starting 23:00 is my Asian session OR, the other one is my London lession OR.
Take note of the 24th of January. So it confirmed an A-Up during the Asian session, and as far as I can see, I don't think the A-Up actually became a visible S/R level in the TA sense during the Asian session itself. However, later on during the London session, the USDJPY actually made a failed A-Down, hit the previous A-Up from the Tokyo session the bounced all the way up.
Actually the A-Down from the London session of the 23rd acted similarly for the Tokyo session of the 24th, but then in that case it seems that it more clearly "became visible" in the TA sense.