Rgular +5 or +10 MPH out of big city, no more than that. It's all about average speed. Stop, Gas and go... and try to avoid traffic as much as you can.
SS1000 is 1000 mile sin 24 hrs. It's a long day but you have plenty of time to get it done. Pushing it you can event start after dinner and stop for a short night of sleep and hope not to get any traffic.
1500 miles in 24 hrs is a different story. Not a lot of margin. I cough some traffic in DC, lost about 1 hr. I didn't stop for food, only eat whatever I packed in my tank bag. Fill it up with snack bars and a 3L camel pack with Gatorade. I refill the drink during the ride. Other that that I stop only for gas and hit the bathroom if needed. I stop once between Baltimore and DC. It was in the 40's when I left Laconia and it was getting seriously warm with all the gear and the rain suite over. Once pass DC traffic it was a one shot deal to West Palm Beach... Gotta love Sundays!
Since no ride is perfect without a not so funny moment that end up to be funny after the fact. I drove through NY on I-95. Not crazy about it but I figured out should not be too bad on a Sunday morning. By the time I get to NY I need gas bad!!! And taking a monster piss too. So I end up in the middle of the Bronx on a little gas station about the size of a bus stop. Fill the bike up and no pisser!!! Now keep in mind that I'm having cramp since I've been holding it for about a solid 1hr. I get on the bike and take off... without pipi. By the time I get to the end of the parking lot I'm almost in tears... I gotta go now! So I just decide to let it rip... f%^$ it! Can't be that much in there anyway... I was wrong! I could feel it dripping down my legs... I was like "Not my boots!!! So I put my foot on the pegs not to fill my boot with piss. By the time I'm all relief and good to go I look at my pant... WTF!!! I had a rain suite on... no liquid in, no liquid out!!!
I gave one of those Chuck Norris sidekick to let the waive of piss leaked out, put it in first gear and never looked back. Never been so happy to have a helmet with a dark visor on...
I laugh about it now but it was so discussing...