Second membrane sweep?

I am about to get my second membrane sweep done for this pregnancy today. The first one was done at 37 weeks 4 days and today I am 38 weeks 4 days. The first one didn't really do anything except for make me lose a little more of my mucous plug and I cramped for the first couple hours afterwards, no bleeding. I was 2-3 cm dilated and 50% effaced. So my question is anyone who has done a second membrane sweep, did the second time do it? Or am I just wasting my time?