I have mentioned this before but after successfully using it a few times I thought I might bring it up for full discussion.
whenever I get a brew which seems to float around the 1020 mark (seems most do) I find a teaspoon of DME fires it up and within 24 hours its done
my theory was at 1020 the harder sugars to break down are left, and giving the yeast something nice and easy to munch on it just uses its momentum to carry on with the rest.
feel free to flame me down, I am expecting it, just found it works to finish of primary with ease for me
DME restarter?