Lieu days and a roster

Hi guys,

Trying to figure out a lieu day situation for my workplace.

Situation is I work on a rotating roster. With 2 set days off per week, these days rotate weekly so eg. One week I will have M and T off, then the following week will be T and W and so forth. Our contract states we are available for regular work on days from Monday through Sunday (every day of the week)

We have the option to voluntarily work (if there is the demand for it) on our rostered days off, which is paid at time x 1.5 for any hours worked, as well as 1.5 for the stat day, this is paid out on TOP of our fortnightly salary payment. This cycle my days off landed on Friday and Saturday, due to high work volume I was offered work for the Friday, and accepted the offer. Several of us on the same roster who worked are unsure about whether or not we are entitled to a day in lieu for working the Friday as it is not our regular working day for that week yet frequently work Fridays.

Does the rule of "regularly worked X/amount of Fridays in the last period of X weeks" apply here? Meaning the Friday is technically a regular working day? Or does the fact that it is a SET day off mean that we are not entitled to a lieu day?

Any help appreciated