Yes, you absolutely have to ping your interior links. Google will crawl less than 5% of the links inside your feed naturally, even after many days. Also, if you are using a free service you'll want to ping your links more than once. Typically Google will not crawl a huge percentage of the links so you need to ping more than once. (That's actually why we implemented crawl tracking in Linklicious - to guarantee full crawls)
Be careful pinging too many at a time as well. If you go from building 0 links a day to forcing google to find 1000 or 5000 in one day, you are playing on the bleeding edge. We've had many, many reports of people dancing/sandboxing from pinging hundreds a day - and why we default the drip rate to much lower.
Pinging is an amazing tool to maximize your link value, but think through it logically and ask lots of questions.
