Is it really true that 20mg XR is equivalent to 60mg of regular Adderall? This is what my doctor told me...

I've been wanting to try the XR instead of the regular Adderall for a while now, and today my doctor prescribed it. One problem: my normal dose is 60mg, and he lowered me to 20mg XR, 20mg regular Adderall.

HE said that 20mg XR was equivalent to 60mg of the regular stuff... I have a hard time believing this, considering that most people I've known on the XR are on 40mg (and had been on 60mg of regular Adderall).

Thanks,

Jess