When is it advisable to flatten an image in Photoshop?

Flattening an image in Photoshop is most advisable when preparing the image for final output or print. This process combines all visible layers into a single background layer, which is beneficial because it reduces the file size and ensures that all visual elements are rendered as they appear without the need for references to separate layers. It simplifies the file, making it easier to manage and ensuring that any adjustments or effects are preserved as part of the final image.

In the context of outputting a file, such as for print, flattening ensures that there are no unexpected artifacts from unmerged layers or issues related to layer visibility. This can also help achieve consistent results in different programs or when sending files to other users, as they may not have the same layer structure.

Editable layers and the ability to apply filters and change blending modes pertain to situations where maintaining the flexibility of an editable project is required, which is not conducive to flattening. By flattening the image, all those editing options are lost, solidifying the image into its final state.