| Clue | Source | Date |
|---|---|---|
| Freely admit a dumped settee proved useful for ages | ||
| Proved to be effective over a period (4-6) | ||
| Proven over a long period | Universal | 30 Aug 2020 |
| Borne out long-term | The Washington Post | 05 Oct 2019 |
| Borne out long-term | LA Times Daily | 05 Oct 2019 |
| Borne out long-term | ||
| *Proven longterm | The Washington Post | 04 May 2017 |
| *Proven longterm | LA Times Daily | 04 May 2017 |
| *Proven longterm | ||
| Proven over a long period | ||
| Tried-and-true | ||
| Proven over a long period | ||
| Lasting for years | ||
| Proved through long usage. |