High resolution images come standard in all commercial, event, and wedding packages. They are also included in the all-day portrait sessions as an incentive.
All portrait sessions that are half-day and shorter include only fully retouched Enhanced photos in high resolution. Their number depends on the length of the session, usually from 5 to 20. These are the images ready for their spotlight in BIG sizes, like posters and wall art.
Our main reasoning is that to maintain the known brand identity, we discourage printing large photos which were not fully retouched. All those un-retouched photos (a.k.a. proofs) are just the "directions" to the Enhanced images, the final images that reflect our intended vision and are given to you in their full glory. :)
However, you will get all the proofs! They will be in a social-friendly size and you can still make small prints with them.
The second reason is mundane—profit-making. If you must have the high resolution images from your shorter portrait session, they can be purchased either individually or as a whole set at a discount.