"At one time I modified an old mechanical (daily) timer" - back 20 years ago I used one of those with a 60 or 30 min on-time to keep cells charged, vs a low level trickle charge.? Back when we didn't have Eneloops that just stay charged.? Back then, though, NiMH really took damage from over charge.? Back when <1500mAh was SoTA.
As for cooking, don't worry for short term (like a full 24h) overcharge at 0.1C on a factory pack.? One reason they may have picked such low-capacity 1400 cells, originally, before the?smart charger was popular, is that they can tolerate overcharge MUCH better than higher 1700+ cells.? Sure, it's _better_ to turn off when full (by time, or when they get a little warm), but a day won't make much difference.? Leave 'em on for a week, and sure, that's far from ideal.
radellaf