The stories of upgrade success vary massively - more often than not reports of lower status getting targeted "taster" upgrades - to entice them to book higher cabins.

What I know from personal experience is booking WT+ on single traveller tickets, on busy routes as a Gold, on High J config aircraft - low amounts of WT+ has a decent chance of operational upgrade.

I wouldn't make any status decision based on getting into CE. Just not worth the time thinking about it.