The standard text of the Mi She-Berach prayer for the sick asks that G-d send healing "to his 248 limbs and 365 sinews."
What if someone, G-d forbid, lost a foot a few years ago; and now prayers are being recited for him (for some other condition)? He doesn't have all 248 limbs. (Unless you tell me it's intended according to R. Hayyim Vital's writings that we have 248 spiritual limbs in our soul too ...)
And for that matter, what about someone with polydactyly (extra fingers and/or toes, assuming they're in good working order)?