The Heartguard will get some of the worms. Sentinel gets more (e.g. tapeworm, whipworm). For the most part Sentinel especially should keep the worm population down to minimal levels.

The game I play with my Vet is that puppies go in for their yearly examination. When they ask if I want a fecal exam- I decline. I then inform them to provide me with the Panacur. The idea being that they probably would come back and tell me the dog has some form of worm, and/or prescribe the Panacur anyway. Thus I save on essentially a worthless fecal exam charge. The one time they came back and said there might be some worms, and prescribed Panacur. So again, why even bother with a fecal exam?

My next one is due to go in the early part of December. I intend to purchase the Panacur online since it's non-prescription, and cut costs more. The Vets are gonna hate it.

For those not familiar with Panacur it comes as a powder in 3 different size packets. You can buy the appropriate sized packets that add up to the weight of your dog, which equals one day's dose. The powder is sprinkled over their food once a day for 3 days. Both of my dogs didn't object to the taste. However one had an upset tummy after day 1. Pre-dosing with Zantac fixed that.

Note on tapeworm. The dog has to ingest a flea, or the flea's feces to become infected. My parent had two dogs where only one ever got tape worm, and she repeatively got infected with it. The dog liked to "groom" the other dog by licking it. Thus it consumed flea feces, and infected itself. Sometimes it just doesn't pay for a dog to act like a cat.