I'm drinking RLT when I remember. Some women have it throughout pregnancy. Remember, it doesn't induce labour. It's a uterine tonic, so it's meant to make contractions more efficient when they start (not actually start them off). I drank it the first time, and I'd say my contractions were pretty efficient, as my first baby was born after a labour of under eight hours.
As for EPO, I'm not using it this time, as it's been linked to PROM (prolonged rupture of membranes), which is when your waters break and labour doesn't start for a long time. When that happens, "they" worry about infection and often want to induce you if labour doesn't start after a certain point (of course, you would have the option to decline induction and monitor for signs of infection, but women often get told "we have to do xyz" instead of being given options).
Edited to add a link to an article that discusses studies: https://vbacfacts.com/2012/11/13/evening-primrose-oil-dont-use-it-if-you-are-pregnant/