Over-hangs in prints
It is typical for a 3D printer to be able to manage one-half the width of the nozzle for unsupported layer printing. This frequently calculates out to a realistic 45° from the start point.

If you are getting 1 mm extension from a 0.4 mm nozzle you are doing well. It's possible that the layers are not strongly bonded at the point of extension from the vertical wall, but are then strengthened by the layers printed above, if they do not extend excessively.

If your part is designed well, the extension will be distributed gradually over more than one layer, allowing that 1 mm extension over 2.5-3 layers without impacting the appearance of the model in an excessive manner.

The above does not apply to bridges, as it involves a different dynamic for the printer/slicer software.