@Kalmnir So it is a balancing issue as at the moment, the game is designed to work in a way that the carriers bring in the resources to these sort of buildings for them to work but in this case, the carriers are not prioritizing this task well enough - so there comes the balancing issue. We need to find the magical "number" that would bring perfect balance to how often they carry these resources but also how often do they gather resources from deposits, carry resource boxes from the ground to the storage, carry resources to construction zones and build them - and all other tasks they have and possibly will have in the future. And of course, they are only humans, they still need to eat, sleep, wash, get treated and have some fun too!
And that is why we are still working on it, trying to find whatever would be the best solution for this. Please do keep in mind that as we are still in Early Access, these sort of issues are going to exist for a while as we try different ideas on how to best fix it.