Maybe my question is very silly

Hello, my question is that I only want to read some sensors connected to the pcf8574at pins, it is not clear to me what mode I should use for this purpose, I read everything as 1 byte or I should read them separately as uint8_t val = pcf8574.digitalRead(P1); uint8_t val = pcf8574.digitalRead(P2); uint8_t val = pcf8574.digitalRead(P3); ....etc