How do you tell a one-time goodwill impairment from a structural loss of value?

is a past goodwill impairment a one-time event or a symptom of structural problems? Indicators of 'one-time':

• A specific trigger — a pandemic lockdown, a regulatory shock (the glyphosate litigation at Bayer-Monsanto), an unexpected market disruption.
• Operating performance stays stable or recovers after the impairment date.
• The CGU remains profitable on a run-rate basis.
• Management has implemented clear, documented restructuring measures. Indicators of 'structural': (a) repeated impairments over 3+ years — see ProSiebenSat.1 (TV-advertising disruption from streaming) or Deutsche Bank's asset-management arm. (b) Structurally declining margins / EBITDA erosion before and after the impairment. (c) A 'goodwill yo-yo' across several of the group's CGUs. (d) The goodwill / EBITDA ratio grows despite the impairment because EBITDA is falling. (e) Industry-wide disruption (print, brick-and-mortar retail). DD implication: for a 'structural' pattern → adjust the valuation with (a) a lower multiple, (b) a more conservative forecast, (c) a higher equity discount.