Harold there's rarely any "one size fits all" when it comes to planted tanks
IMO the more water changes you do, the more beneficial it is for the fish. However, you read correctly that in a low tech tank too many water changes can actually strip the water of nutrients (mostly nitrAtes) for the plants.
If you're willing to test your nitrAtes regularly and experiement with different amounts of water changes, this might help you figure out what exactly is the right balance for YOUR particular tank? IMO nitrates between 10-20ppm are ideal for most planted tanks. Ammonia and nitrItes of course should always be 0ppm...
What about adding some shrimp as a cleanup crew instead of cory cats?