Page 43 - Patty Hahne "The Pocket Guide to Prepper Knots"

Depending on factors like the material the rope is made
from and its thickness, you’ll discover that some types of
rope create quite a bit of friction when a knot is tied in
them. Remember, it’s this friction that can make untying a
knot very difficult.
Other types of cordage are slick and don’t hold some knots
very well at all. An example of this would be monofilament
fishing line or rope that feels like slick plastic. A knot that
might hold just fine with thicker rope can often slip and untie
itself under tension when using monofilament. The number
of inexperienced anglers who have tied a hook or lure onto
their fishing line, only to watch the knot become untied when
they hook a fish, would be way too high to count. Luckily for
you, this book contains instructions for tying several good
knots that aren’t typically prone to slipping.
Considering that certain knots can slip when tension is
applied, some people choose to tie stopper knots in the
leftover length of the working ends of rope as an added
precaution. The reason for doing this is that if the rope slips
and the knot begins to become untied, the stopper knot
may help to prevent it from slipping enough that it becomes
completely untied.
You should know that it isn’t usually advisable to trim the
working ends off close to the knot. Doing so might make the
knot look a bit tidier but it could increase the likelihood that
the knot could slip and become untied. It isn’t uncommon

Something to Consider Before You Tie Any Knot 37