You have to be careful with those battery adapters. C and D cells are larger not just to give more mAh’s but often to deliver higher continous current i.e. more mA’s, and AA or AAA batteries similarly loaded may be prone to over heating. If you know the D or C cells are simy to give a longer operating time, you are OK, otherwise you may get a device meltdown (or even battery explosion). That being said, I use them all the time in flashlights that have been converted from incandescent to LED as the LEDs usually need about 1/8th of what the incandescent bulbs did.
I have one of those hand wave paper dispensers that you usually see in bathrooms. That one takes four d batteries. That’s where I use my adapters. It’s better with rechargeables because when they’re out it just stops working.