Yes test with prepaid sim cards of different companies. Theoretically speed should be independent of prepaid or any contracts but I have doubt about the services provided by virtual network operators e.g. Yallo which uses sunrise network. During peak load sunrise might like to provide better service to their customers.

Other than also depends a lot on devices. If we talk about 4G devices, some does not provide any carrier aggregation or only 2CA then max speed will be low.

https://en.wikipedia.org/wiki/List_o...h_LTE_Advanced