I found flyzed quite conservative I have never seen a smiley face since they exist, generaly but not alway a face with - means you have a chance but when it is really sad it means the plane is quite full.
Make an experiment lokk at the exact loads for a flight on your airline then go to flyzed for the
same flight you will see.
To be short I tend to trust totrust it for the very negative but after.....
Of course when nonreving we are used to the incertity so we never know until the plane takes off.