It depends on whether they know what they’re doing, and whether they have the chops.
One well known vocalist who is a friend of the family, and has played full time for about 20 years, has almost no speaking voice left. He can still growl for an hour every night, though.
People that sing from the throat tend to burn out quickly. If one projects from the abdomen, they’ll do better and end up less damaged.
Hubby has been a part time heavy metal vocalist for 25 years, and still has his full vocal range.
No lozenges, but an occasional shot of Rumpelmints (sp?) doesn’t hurt