The "append" geoprocessing tool's "Field Matching Type" parameter should default to "Use the field map to reconcile field differences".
In the last two companies I've worked in, our inputs are always weird datasets from random places into other datasets, so our schemas never match. Possibly twice in my career have I left this parameter as "input fields must match target fields". The tool fails if this is left as the default for mismatched input schemas.
It's always a talking point to new trainees and wastes time to always have to change that input for a commonly used tool.
Theoretically, even if folks heavily utilize the default parameter, their append would still succeed with the default changing to the field map to reconcile field differences, as it would autofill their matching fields.