Exactly.
I let them stretch by playing and constantly retuning, and
not by pulling on the strings, which for me always causes intonation problems.
Some folks love to do that, but it is not the method I use. I prefer to 'let it happen' from string vibration, which takes anywhere from 8-12 hrs of actual PLAYING time and can be done in about 10-14 days, which is fine by me.
Multiply this effort across a set each of soprano, concert and tenor strings, on three different ukuleles, one of each scale lengths, all restrung at the same time, with the new Aquila CarbonBlack strings, and it's lots of playing and retuning, all of it therapy for me which I do not mind in the least, and it forces me to practice more any way. :music:
To me, pulling on the strings is akin to yelling at the yeast in your freshly mixed bread dough, demanding the bread to rise FASTER, and it does so begrudgingly and with resentment. Not a nice start to a relationship.
Patience is a virtue.