Adhesive Not Dry: Manufacturers recommend a minimum amount of time between the installation and the start of heat welding, generally overnight (except when using a dry-to-the-touch adhesive at the seam). The reason? The high heat from the welder will cause any moisture in the adhesive to turn into moisture vapor that will stop the thermo-fusion process from thoroughly taking place. The time between the installation and welding is worth the wait.
Straight Edge and Butt: The straight edge and butted seam is used by a lot of installers. They use this method not realizing the seam edges are gapped in some areas and tight in others.