Many people say bad things about progressive rendering with Cycles. E-Cycles is the exception. Look these render times below.
BMW scene - RTX 2060:
E-Cycles - Final render (Progressive refine) - 1:10
2.79.7 - Final render (Progressive refine) - 7:19
2.79.7 - Final render (Tiled) - 2:16
It’s faster than with tiled rendering