I have always heard that anything under 5 minutes MIGHT give you unevenly. However, I have never experienced that. I don't routinely use shorter times than the 6 minutes. I use ice to cool the working solution of HC110 before I use it if I have to because the water coming out of the tap most of the year here in N Texas is above 68 degrees f. I, also, don't find the times for development to be different between old and new Tri-x. YMMV.