It’s pretty normal to have devices out in the elements now, it’s just a matter of how many. Yes having a device on literally every plant will probably always be overkill, unless they are so cheap and easy to replace that it doesn’t matter when one gets damaged. More likely it’d be optimal to have a device every x-number of plants - which is what’s done now but the number of devices per number of plants needs to be higher than is currently conventional to increase precision.

Having machines moving around taking readings “each day” is insufficient, as during hot conditions the soil/plant moisture changes too rapidly. You need to take readings at least once every hour or even every 30 or 15 minutes in order to be able to start irrigating immediately when the moisture level starts dropping rapidly.