I know that the battery life on the Mavic air is 21 minutes and that seems kinda short considering the wind conditions and everything. I have a p3s and I am thinking of upgrading to a Mavic air. should I upgrade or not?

Real flight time (down to 30%) is around 15-16 minutes depending upon what you are doing - is than enough for you?

Yes, I think MA is significant upgrade over p3s. I think battery life is great if you consider how small MA is.

Yes it is a significant improvement over the p3s by a long shot. The MA is superior in every respect. (My opinion)

I don't get more than 16-18 minutes on any of my flights!

I average 15-18 minutes. With 3 additional batteries, I have plenty of flight time. This is one sweet flyer. I enjoy my MA.

Yeh same as others, usually max of 15 minutes (but it has been cold and windy) and at least a third of that is in Sport mode. I find that going through 2 batteries in 1 go is usually enough at the mo.

If you care about flight duration, the MP or MPP is the better choice.
That will give you about 5 to 7 real minutes more in the air.
(compared to the real time users are getting with their Air).
Now I like to stay on the safe side of the battery and return around 30% or something. But that is just me

I consistently get 25 minutes off of each battery with my MPP so burning three from 100% to 15% gives me around 1 hour, 15 minutes flight time without touching a charger - more than enough. I have even got up to 28 minutes on some flights. Amazing flight time for what is also a highly portable drone.