Cosmetic veneers can be installed in one session in some cases, and this depends on several factors, such as:

1. Type of veneers: Some types of cosmetic veneers, such as veneers, can be manufactured in the clinic using CAD/CAM technology, which is a technology that uses a computer to design and manufacture veneers in the same session.

2. Number of teeth: If the case is simple and requires placing veneers on a small number of teeth, they can be installed in one session.

3. Installation technique: The one used by the treating physician may affect the number of sessions required to install the veneers, as digital touch techniques or other techniques that facilitate the process of installing the veneers can be used.

However, in most cases, installing cosmetic veneers requires several sessions, as the teeth are prepared in the first session, measurements are taken, and temporary veneers are installed, and in the second session, permanent veneers are installed after being manufactured in the laboratory.

Therefore, a dentist should be consulted to determine the number of sessions required to install cosmetic veneers according to the patient's condition.