Effect of Heat Treating One Limb

I'm re-heat treating the limbs to put back a hint of reflex and stiffen 'em up before final narrwing of the tips and tillering it back the last few inches.
I did a brief video to show some of the process:-
https://www.youtube.com/watch?v=kM1_A2A0_TI
Here's a pic of the bow braced after having done just one limb. The difference between to two limbs is very obvious. Note:- I didn't draw the bow as it would over strain the untreated (weaker) limb.
Why does it need heat treating a second time? The heat treatment probably only penetrates 3 or 4 mm and during tillering some of that wood has been removed, also the bow will inevitably take a little set.
I'll go out and do the other limb now.