Tell me about it. 'Applies to darned near ANY project...including 'fabing' copper drain lines for the high pressure relief valves on a couple of hot water heaters. Ask me how I know...
'Going back to the freakin' hardware store tomorrow...
Larry,
Every plumbing project requires at LEAST three trips. You will have one fitting that is male vs. female, the wrong size or missing a seal. Any flex lines will be too short. You will not have solder, flux or PTFE.
You will have a full assortment of valve washers but NOT the particular one you need. The packing rope you have will be 3/16" too short to do the job.
And plumbers will tell you "everything you need to know about plumbing: Hot on the left, cold on the right and turds go downhill"