Raw food AND kibbles

I thought I read somewhere that you shouldnt feed both raw and dry food because of the different rates of digestion for the foods - sort of like not eating fruit right after a heavy meal...

Is this true?

Cos I think it would make feeding raw harder, as the cats are used to having dry food to nibble on, and also we have 5 cats and they all like to eat at different times in the day

Thanks!

with my dog I give her raw morning and evening .. she gets dry in between, just not at the same time