Just from watching a few games.It seems as if teams in 3 rd and 10.Have a lower chance of picking up a first down.Yet if a teams is anything over 3 rd and 10.Say 3rd and 11,12,13,14 and 15 and above.You seem too have a better chance at picking up a first. down.I have noticed a lot of long 3rd downs being picked up.

There's no inherent logic to improve the odds of a long play on 3rd and long. I actually recently ran the numbers in another thread (you might see if you can find it, I did a quick search and didn't so I'm not exactly sure whether it was in the community form or in a league forum) and it's not as high as it feels like. It does seem like a lot when I watch the NFL, too, but that's probably because you notice it when it happens (especially against your team!) and don't when it doesn't.