This is a great set by the The Tannahill Weavers!
Knowing a tune is good.
Knowing a set is better.
Being able to play a good sounding set that also lets you check the tuning on your pipes is the best.
Having a good tune, or set, that allows you to make sure everything sounds correct, but you can also use to entertain, kills two birds with one stone and gives your repertoire depth.