I've tuned the clock 3 times since the last update. Before these, the last time had been September 27.

2023-12-27: Battery: 2.973; tune: 40/32 sec late: new error: -7.44
2024-02-14: Battery: 2.924; tune: 40/32 sec late: new error: -7.73
2024-03-27: Battery: 2.881; tune: 48/32 sec late; new error: -8.14

There seems to be a steady slide in the static error; I'm thinking I might be able to extrapolate from this and add an aging factor to compensate for most of it.

The clock started its life on the final PCB with the current battery on March 16, 2024, over a year ago. I haven't drawn the voltage curve on a chart yet so I'm not read to speculate how long I expect it to go, but so far I'm pretty content - comfortably over a year is fine with me!