Physical chemist here. You pick your dating method depending on the period of time you want to date. Since all dating methods depend on the half-life of the isotope to work, using short half lives to measure long stretches of time will fail.

C-14 has a half life of about 5.7K years. So every 5.7K years, the amount of C-14 compared to the original halves. The limit of C-014 dating is about 50-60K years (way beyond the young earth creationist opinion on the age of the earth).

But other isotopes have much longer half lives and thus can be used to measure longer time stretches. And best of all, multiple nucleotides with different half lives agree on the elapsed time to within a few percent. From wikipedia:

For example, a study of the Amitsoq gneisses from western Greenland used five different radiometric dating methods to examine twelve samples and achieved agreement to within 30 Ma (mega-annum; million years) on an age of 3,640 Ma.[8]