Why do I find only some timecard records in the HXT_TM_HEADER?

Summary:

I am trying to build a BIP report which contains information on the timecard details and I have understood that the best tables to use for this purpuse are HXT_TM_HEADER, HXT_TM_MTRX, HXT_TM_MTRX_DLY_ATRS however I found only some records and not all the timecards (as expected).

Content (required):

I am trying to build a BIP report which contains information on the timecard approval status, who approved, the quantity of hours per day, etc.

I have understood that the best tables to use for this purpuse are HXT_TM_HEADER, HXT_TM_MTRX, HXT_TM_MTRX_DLY_ATRS however I found only some records and not all the timecards (as expected).