that's not overwatering..
1) always fully medium - if this causes a problem it's jsut a shitty constituted medium.
2) wait for apprprieat dryback.
Rarely do people overwater by giving too much. More often it is about frequency. Not waiting for enough dryback. If soiless, also ensure 10% runoff out the bottom, religiously. Deviating from this is simply doing it wrong.
Stop choosing the volume in some top-down inductive way. You give the volume necessary to accomplish the task. If you wait for same dryback/loss of weight, it will require the same volume. you only learn in hindsight. Same with time between -- you do not choose this in a top-down way. you react to proper dryback. Observe and react.. you do not choose volume or frequency in the general sense. There can be variability in time between, but some minimum safe dryback is necessary.
Plant in first picture is low on Nitrogen. paling tip-in on leaf and bottom-up on plant. Some symptoms are less discrete, but this one isn't anything else.