Which type of tip is usually altered at the well line to expose more of the natural nail?

The partial-well tip is designed in such a way that it can be altered at the well line, which allows for a greater exposure of the natural nail underneath. This design is beneficial for achieving a more natural look while also ensuring a secure bond to the nail plate. By trimming or modifying the well at the appropriate line, technicians can customize the fit of the tip on the client's nail, accommodating various nail shapes and preferences.

Additionally, the partial-well tip construction provides versatility; it allows for adjustments based on the length and shape desired by the client. This feature distinguishes it from other types of tips that don't offer the same level of customization.

The other options do not possess the same modifying capability at the well line. Full-well tips typically cover more of the nail and do not provide the same exposure to the natural nail as partial-well tips. Half-well tips also offer limited exposure, and regular tips generally do not have a specific well design that can be modified. Therefore, the partial-well tip is the clear choice for achieving the desired exposure of the natural nail while providing flexibility in application.