Quick answer: Cross-platform bugs (PC/console/mobile) need cross-platform bashes. Testers on different platforms in parallel surface bugs single-platform testing misses.
Bugs that affect one platform are different from bugs that affect another. Test in parallel.
One tester per platform
PC, console, mobile. Same gameplay objectives; per-platform notes.
Compare findings
Post-bash: side-by-side. Platform-specific bugs surface; cross-platform too.
Tag per platform
Reports tagged. Triage filters per platform.
Test the join points
Cross-platform multiplayer; cross-platform save. The interfaces are bug sources.
“Cross-platform testing is exponentially more useful than per-platform. The bug surface is at the interfaces.”
If you ship cross-platform, the cross-platform bash is non-optional. Plan it pre-launch.