I think it was Zz Yzx who stated:

I just bought and installed a new Whirlpool Energy Smart water heater.
It's been running for a couple weeks now, and I notice that it feels
cool to the touch, while the 20-yr-old water heater felt warm (both
inside and outside the insulating blanket).

Do today's new "Energy Smart" water heaters need a blanket?

Need? No. Can they help? CERTAINLY!

We just got a new water heater, and it's more efficient than the
15-plus-year-old one it replaced, and the blanket is on. More
insulation is better than less . . . .
--
"Trust me, there is NO way to nonchalantly conceal the fact that you have a
power tool in your head, no matter what you do." -- El Gato