Yes, your 10 track joints per block will be fine. According to Barry's book, track blocks should not exceed 5 to 6 sections of track on each side of the DCS/power connection to the track. That's not word for word from the book but it's very close.
It goes on to say, Each track section counts as one section regardless of it's length. In any case track blocks should not exceed 100 feet in length.
Also, it sounds like the center of the block is what Barry is saying for your block connections.
Although Barry is no longer with us, the book (DCS Companion for TIU & Remote) is still available and is well worth the cost if you are running DCS. Lots of good information in there that is not in the DCS manual. There is also a Wifi version (maybe Wifi Companion, but I forget the exact title?) that covers DCS using the Wifi App.
Edit: What Royboy & Tom Tee say about having only one feed per block is also a very important rule to follow with DCS.
