That is definitely more of the case. Especially with regards to battery powered sensors. Most of the sensors out there only send a status when they have a state change. The rest of the time Almond+ would have no idea what is happening with them or even if they are still in existence (maybe they broke, left the range of the router, ran out of power, etc...). If the sensor does not send something different the Almond+ continues to show the last status as the one that was there.
Some sensors are configurable. I have motion detectors that can be set. They default to 5min (they will send a motion detection, then check again in 5 min and change the status if needed). Other settings are 1min, 30min or pulse (which means when they detect motion they immediately check again and send the status again... and keeping doing it until the motion stops).
Some sensors do have regular readings. The new Aeotec MultiSensor 6 will send a few (temp, humidity, and light) readings in real time if it is on AC.
Almond+ cannot poll the sensors either. Not because it is incapable, but because most (I have not found any yet) sensors just aren't designed that way. I would love it if all the sensor designers out there went and added these 2 little features:
1) A regular, once a day (or better yet configurable) status, just to let the controller know it is still alive and kicking. That way you can make something in a controller that says if it does not get a status once a day you need to check the sensor.
2) When the sensor sends that regular status it asks the controller if it "has anything" for it. Firmware updates, status frequency changes, whatever. It is just an opportunity to have it check and be checked. Just to make sure everything is good.