Many workshops don't do any major engine and gearbox repairs, but often simply exchange the whole unit in case of signifcant damage. This is (for the workshop) an easy, but (for the client) often an expensive way to fix such issues. Besides that, in some cases it's a constructive problem of some parts that cause the damage - so with a new, non modified unit, the same incident may happen again and again.
We have a different approach.
We maintain and repair sports- and racecar-engines as well as sequential, manual, dog-ring-, dual clutch and synchronized racing gearboxes and differentials of different brands since more than 15 years. If there is a (major) problem with your engine or gearbox, we always take a closer look on the issue and check torough if a repair is possible and makes (financially) sense. If we identify any weak point/weak component by design of the OEM part, we can use reinforced components for the repair to prevent the engine/gearbox from having the same problem again in the future. During the analysis/repair process, we do a full documentation of the damage and parts changed.