I usually stop with 2 tries and will allow an attempt to go for 30 sec, this is variable depending on how badly I need a line. If a pt is crumping, Im not going to stop until I have access of some sort.The best trick I have ever learned was from a flight nurse when I was a new ED tech. Instead of advancing just the angiocath once you have a flash; pull just the needle tip back into the catheter so its no longer exposed, and advance the entire unit. This keeps the cath ridged and allows you to have better control while your advancing into the vein, without causing damage to it. It works great for those fragile old veins that have been wrecked by heparin as well as tiny peds veins with strong valves. I also am a big fan of hands for a 1st try because you can hold traction easily, they are usually easy to visualize, and you are leaving superior options for access incase you loose a line. Obviously if your needing to drop bilateral 16-14 this should not be your 1st option. Also don’t forget the “handcuff" vein, many people forget its there, but it can be a great option.