A lead battery does need to regularly get to mfg defined 100% Full state in order to maximize longevity.
Besides setting Absorb V at the high end, that needs to be held long enough to get there, even if 95% of the charge current is not being accepted for the last few hours of the charge cycle.
Of course other concurrent loads can change thing, need to keep any trivial "load dumps" from preventing that "long tail" process.
Of course going past the endAmps stopping point for too many hours too frequently can reduce AGM
longevity, FLA just need to keep watered.
But that is very rare, and usually impossible with most solar
setups, given the sun usually sets.
Going to Float **way too early* is very common, maybe 90+% of charge sources left at their defaults.
But cross-referencing whatever Absorb Hold Time and Absorb Return adjustments the source allows against an ammeter regularly, those two goals are not that hard to balance, as you get more familiar with usage patterns vs changing conditions, can become instinctive.
Of course the ideal is shunt-based charge regulation that transitions to Float based directly off trailing amps acceptance hitting the endAmps spec.
As a bank ages and wears, this gets harder, takes longer, and at a certain SoH% does eventually become impossible to reach the spec'd endAmps.
Nothing to do with overcharging, and may in fact indicate it's time to schedule replacing that bank.
An alternative spec to use is Deka's:
> Absorption End Point = Current change over 1 hour period of less than 0.1A
Note the*current***change** point there, no actual absolute value given for endAmps
Thus it will work
even with an old worn-out no-name Wally's batt that has trouble hitting .05C
But when that batt is fresh and new, and you can't find the specific protocol from the maker, then .005C is a good default to start with, especially for FLA.
For a sub-par*AGM, maybe use .02C if you're worried about overcharging.
As a side note, if you can't easily find detailed specs like endAmps from a batt maker, it's a sure sign IMO that you should avoid*purchasing*that brand.
The point is to have an objective benchmark to hit consistently "most cycles" if possible,
rather than assuming your charge source's "going to float" is an indicator of the bank being Full.