Don't forget to take into consideration the base station, aka signal tower, of the mobile network service provider when talking about higher CAs.
In the same way that buying a 5G device doesn't guarantee 5G performance in an area where the towers aren't configured to provide 5G access, the same goes for carrier aggregation. The tower dictates how many bands the device will aggregate (that the device CAN support), not the other way around.
So you might be impressed of 5CA (Cat.18) or even 6CA (Cat.20) LTE devices and how much theoretical bandwidth you think you could get from those, but with the current situation here where I have yet to see an area where towers provide more than 2CA or Cat.6 of LTE service.
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