I've had it go both ways. It will strongly depend on the hen. One took the chick back after 3 weeks away - yes, weeks. It was a bad break in 2 places and it had skinned its leg 3/4 of the way around - got the leg stuck in a place where 100+ chicks had been in and out and around … and never gotten hurt, sigh, then struggled to get out until I got home and found it. There were only 2 siblings to the injured chick, so I had that one with me at all times. Actually when I returned him, part had healed so I could pin the rest of the leg up, and as soon as I did that, the chick started scooting around like nobody's business. So not only did she take him back, she accepted a chick hopping around on one leg, as did his sisters.
The other time after 3 days for an injury that had some bleeding, the hen rejected both the injured chick and its companion (8 chicks, so mom kept 6)- so they grew up together separately until mom weaned the siblings and stopped making momma hen noises. Because of course they would hear her and think MOMMYYYYY!!!! And she would go after them, and the siblings (unfortunately mostly cockerels that time) challenged them too when mom chased them off.