Timing tells have been invaluable to me. They can tell me what someone has or doesn't have. I agree that instant action can often mean something, but sometimes delays do too. One of the first tells I remember picking up was that if someone acted in a short or regular time length to be the PFR and then AFTER the flop waited a long time and checked, it usually meant weakness. They take their time to try to intimidate like they are weighing out the right amount to bet. If someone takes their time and check/calls your PFR and cbets on 2 streets on a drawy board and then auto-shoves a blank river, I've noticed that is often a bluff. If they had a good hand, why would they autoshove or not wait for you to bet first? Why would they never put in a raise or bet of their own? If you can contrast actions and put the pieces of the puzzle together, you can extract good information. I think about my own tells and use that as a basis for villain tells plus whatever I observe. No one piece of information is reliable by itself, but if you look out for information and see multiple occurrences, it can be reliable for specific villains. Plus, you can develop default timing lines for unknown villains based on the culmination of many villain tells.