What constitutes scuff sanding?

I finished putting down my first coat of poly on wood sanded down to bare wood. The poly sat on top in places, and soaked in on others. Spotty coverage, but that what I expected with all that bare wood:

http://www.flickr.com/photos/8970927@N04/7299506348/in/photostream
Not a great photo, but you can see it is not uniform and the grain is poking through in places.

I then scuff sanded with this pole sander & 220 grit sandpaper:

http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100392838&R=100392838

Not how much you're supposed to sand, but I played it safe by running over each board exactly twice... one with the grain and then turn around and do it again to the other side of the room:

http://www.flickr.com/photos/8970927@N04/7299506900/in/photostream
As you can see the board aren't entirely flat (I used a U-sand pro rental with 4 random orbiting pads as opposed to drum sander), but pretty freaking flat to my eye and hand running over it. Should I be concerned the scuff didn't scuff each and every inch? Should I be going over it more than just up and back with grain? The first coat of poly absorbed into the bare wood so much, I was reluctant to go nuts with the sander for fear of removing too much.

And then there were my lovely lap marks in the first room I did before I figured out the Minwax Super Fast Drying Oil Satin Poly was drying really quickly (didn't help that my newbie self had the house cranked to 80F):
http://www.flickr.com/photos/8970927@N04/7299506592/in/photostream
http://www.flickr.com/photos/8970927@N04/7299507150/in/photostream
I sanded them pretty hard with the 220 on the pole sander. Didn't much care if I sanded to bare wood in places so long as the lap marks blended in better.

So.... should I be scuffing more? Do I need to actually scuff up each and every inch (when the pole sander is laying flat across slightly rippled boards it appears)? Did I make the right call my sanding the crap out of the lap marks area even if it took most of the finish off?

Next coat I know better about the lap marks... figured it out after my first room. I'll also have the heat at 70F instead of 80F.

So far so good for the most part:

http://www.flickr.com/photos/8970927@N04/7299593450/in/photostream

Thanks!

*bump* I'm looking to put down the second coat this evening! Thx.

the finish should have a uniform appearance of "white" after being buffed out..it should not have any luster..thats all I can tell you.

the lap marks would have not proved an issue with the next coat..they would even out.

if you are unsure, take a 150 grit paper( 220 is a little fine for poly) and do ti by hand in a circular motion..keep even pressure .

don't kill yourself on it.. and make sure the floor looks sanded... and you have fine powder..

clean the floor and coat.. this will ensure you get proper adhesion..