Looking online in the past i have seen that lots of people who are not running cab heaters just block off the heater line ports on the housings. Is that not an issue with coolant circulation during a cold start?

I had my top housing one blocked off on the side port but Im running a intake heated system with a ported spacer so I still get circulation thru the block when the thermostat is closed. I was wondering because yesterday I was installing a new heater system in my truck and it just crossed my mind.