Prewashed veggies, do u wash again at home?

After the famous organic spinach scare of a couple of years ago, I've become very punchy about veggie safety. I love spinach, but for a while after this event, I wouldn't touch it. Then I started noticing the pre-washed veggies, 3 time washed, in fact, and I tried it out. I liked it. Add to it the fact it reduced food prepping time a good 20% and I was hooked despite the higher price.

But something in the back of my mind still nags me. How were the packaged veggies, primarily lettuces, kale, spinach washed? 3 times, but for how long? Can bacteria regrow in the packages?

I would love to hear your thoughts on the matter.