How to make two different time ranges periodic in time dependent study

Dear all,

I'm trying to simulate a multi-physics model and one of them is heat transfer. I'm giving a pulse heat source where I use periodic rectangle function. I define the pulse duration as "tt" and the period as "TT". TT is much larger than tt.
Then I use time dependent study and I would like to take 5 values of time in pulse duration and 5 more after that in ONE PERIOD to save computing time. In other words, I'd like to take different densities of values of time in different ranges in one period. And I can make it in only one period like "range(0, tt/4, tt)" and "range(1.01*tt, (TT-1.01*tt)/4, TT)".

My question is how to make this difference repeating in MANY periods.

Is there any expression using mod() to do this or another way?

Thanks in advance.

Best regards,

Chenxi