Hello Aaron, at this time of the year, as summer ensues so hot and dry, I have to water my Plumerias daily here, to compensate for the excessive heat conditions. My side does not get rain anymore for 6 to 7 months, so the plant really gets thirsty.
This is one plant that truly loves as much sun it can get once leafing and awake, but it will suffer when it is not meeting its humidity and watering needs.
Your media looks gritty enough, and as long as there is no soggy part anywhere in the trunk, I will water it daily. I even actually spray the trunk, but not the leaves. It is different if it is rain, they like that better.