Use the mix as evidence
Feel the potting mix below the surface and, if the pot is safe to lift, notice its weight. A dry-looking surface can hide moisture underneath. Check the root zone rather than watering automatically because it is a particular day.
When water is needed, apply it slowly to the mix so the root ball is moistened and excess drains away. Empty collected water from an outer pot or saucer. Water running straight through a very dry pot may leave its centre dry; recheck the mix instead of assuming it is wet.
Keep different needs separate
Mint generally needs more consistent moisture than established thyme. A young transplant also needs closer attention than a rooted, established plant. There is no single volume or interval that suits every herb.
Drooping is a reason to investigate. Dryness, saturated roots and heat can all cause stress. If the mix is already wet, check drainage and exposure before adding more water.
Reference
- RHS: watering (checking moisture and watering containers).