Improvement - import in batches using AJAX or background job?

When doing larger imports it often happens that the import script breaks/time outs.

One possible solution is to increase timeout in the php.ini, but not all users have this ability (especially those on shared hostings).

One solution would be to import items in batches using ajax - this will make the script less prone to timeouts.

Another solution would be to register and immediately execute running a background job using wp_schedule_single_event()

wp_schedule_single_event( time() - 1, 'wp_import_all_things' );

This should start the import job in the background, as a separate process, so, in theory, it would also be less prone to errors and timeouts.

However we would need some indication if the job is running, has run successfully or if it has errored out for some reason.

Any thoughts?

Start by tracing the existing import flow and reviewing the proposed wp_schedule_single_event() call for wp_import_all_things. Compare the batch/AJAX and background-job approaches, then define how running, successful, and failed imports would be reported. Done means large imports avoid request timeouts and expose their outcome.