Be careful on the "medium settling" situation. If it is "settling", it is becoming more compact in the root zone, which is not a good thing.
Mose garden and house plants we are familiar with conduct their gas exchange primarily through leaf stomata, and as they typically grow in soil, usually have a readily-available moisture supply. Orchids, on the other hand, mostly exist as epiphytes attached to trees, or in the case of paphs, grow in the leaf litter on the forest floor, so have a limited moisture supply. As adaptations to favor water storage and reduced moisture loss, the plants have developed vegetative structures that hold water - fleshy leaves and/or pseudobulbs, for example - but have also lost the majority of their leaf stomata, and instead, do most of the gas exchange through the roots.
As an aside, you'll notice the hairy roots on the paph - my supposition is that they provide a bit of an air space around the roots in the leaf litter (something they cannot do in a heavier medium).
If your potting medium is becoming too compact, you can end up suffocating the roots and killing the plant.
Don't panic and think you have to repot right way. If you water lightly, keeping the medium moist but not saturating it, the open pathways between the medium particles will stay open and allow the gas exchange to proceed uninhibited.
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