Holedigger458 has it right.

We have eaten in one premium venue 4 times on one cruise. They actually left word at the main dining room that they have a table for us one night, the last of the 4. It was our 40th anniversary. We liked their small plate offerings. Actually the main dining room had lobster every night, so being limited in the specialty dining was no big lose. More recently we were stuck in our cabin for 5 days with covid. We could order from the specialty dining in our room...not too bad. On the service deck, they have a dining reservation desk (office) specialists to talk to. Not sure if status (level in their program) or cabin level has any impact on success.