Use the current invitation and official instructions as the source of truth. McKinsey Solve has changed over time, so an older guide can describe tasks or interfaces that are no longer current.

Older material may still be useful for transferable skills such as interpreting information, prioritizing decisions, and working accurately under time pressure. The risk is treating old mechanics as guaranteed current mechanics.

Separate skill practice from format assumptions. A reasoning drill can remain useful even if the exact game that originally motivated it has changed.

Build preparation around the assessment described in your invitation. Use older resources selectively for transferable skills, and discard instructions that conflict with the current format. The interviewer should be able to see what you would actually do next, not just hear a general principle. For more detail, see the McKinsey Solve guide.

Current invitation first, old guide second.