I-485 Signature (to Xiaobaitu, other experts, or anyone done thi

Due to the large number of AOS cases, the law firm hired by company will not ask me to sign all the forms (485/AP/EAD). Instead the lawyer asked me to send an email to authorize my signature and they will sign all the forms on my behalf after I reviewed all the forms electonically. Is it a common practice and has anyone done this before? I saw several posts here talking about the rejection without signature. I just want to make sure everything is fine. Any input is appreciated.

BTW: I am EB-2 PERM-based. I-140 is already approved.