Always be sure to synch your knots completely down before testing them with a good tug. In fly fishing, there are already countless variables outside of our control. Gear failure is something you can control. Losing a fish because of a bad knot is something that is avoidable. After every knot you tie, give it a hard pull. I don’t care how many times you have tied that knot before, everyone makes mistakes. I personally would much rather figure out that I tied a bad knot when there is no fish attached..what about you?
More on Knots:
Absolutely.
There is a psychological barrier to overcome of not pulling hard enough. I now test to knot and tippet rating. For example I test uniknots in 10lb line to what I think a 9lb pull amounts to. I don’t tug as there is a risk of exceeding the knot strength.
For Saltwater I have assembled a variety of knot pulling tools, starting with a simple loop of rope over my foot and finishing with custom made knot puller. The knot puller protects your hooks.