Heating times will vary depending on the straw's thickness and material. What you’re aiming for is a soft-glowing orange tip that is fully heated. Once this glow is achieved, no need to heat it much further, another second or two should suffice. It can be a good idea to time your heating as you do it to get a feel for how long it takes on your specific piece and torch. Doing the same for your cooldown periods can help dial in the perfect dab temperature