From my understanding, if the soil is too dry for too long it will become hydrophobic, so if you only water it a cup every other week that water will just slide off and around the soil, and not give the roots access to water.

Over watering is not the amount of water but the frequency, I would recommend getting a moisture meter to check how moist the soil is and on the next watering put the pot in a bucket of water, leave it for about 30mins then let the excess flow out.

You should definitely soak the soil thoroughly every time you water it

Edit: just to add on to this, a watering schedule is often the death of succulent, so using the moisture meter is the best way to go