Let me put it this way. We'll be in Paris for 8 days this summer. And for planning purposes, I've allocated just one day for DLP. Yes, I know it's not enough for anything but the barest taste of DLP. But we're taking this as an educational trip for our granddaughter; to expose her to other people, places, and cultures. There's just too much to see in Paris to devote too much time to DLP, as much as I like Disney. We can always go to DLR when we get back.
I guess what I'm getting at is that different people have different priorities, and we don't know yours. You're getting advice that's appropriate if you were planning a trip primarily to DLP, with Paris on the side. If your priorities are the reverse, are are mine, you'll plan differently. 6 days is not much to see Paris; particularly if one is taken for DLP, one (presumably) for arrival day, and perhaps one for departure day.
-Bob
ETA - oops, I hadn't read the post by Carrie Cat when I wrote that. I agree with her thinking (and am glad to see her say that in 1 day, you can accomplish a lot). Decide what you want to do in Paris, plan it, and then plan DLP. And if you do stay in Paris (we are), a car is a definite liability.