Airlines policy is often subject to the departure airport. By that I mean, in some areas it is custom to allow more carry on, and the airlines often relax their requirements. However if the plane is full, or people are clearly taking advantage then this might not be so. Just because you get through check in and security screening does not mean it's going to get on the aircraft.
It's often frustrating in Economy that some people want to selfishly fill up the overhead bin more than their allowance. My personal policy it this
If I have a ton of stuff (nearly always) I pre purchase additional baggage. Fragile stuff still gets checked but in secure cases - and I've checked equipment that has eye watering value.
The only stuff that goes in the cabin with me, is stuff I need, or want instant access too on the flight in case my baggage get lost or delayed, this means chargers, computer, tablet phones etc
I figure also to budget for the additional cost, that way if I get charge no biggie, but if I don't then it's a bonus. Everyone is different