At least the OM-3, like the OM-1 can keep running for a long, long time. Batteries and electronics are only for the meters in these beauties.
After 37 years owning OM-1's I got my first OM-2(n) earlier this year and it is a sweetheart of a camera. Just so smooth and quiet. Very simple and elegant.
I now have OM-1/2/2S/3/4t/10/40 cameras and the OM-1 will always be my favorite with the OM-2 just a half-step behind.
And with my recent vision impairments, the OM-2 is my go-to since I can't really read the meters anymore.