Does what is stated in "Al-Dhakhira by Al-Qarafi" — that a woman should check for purity when she intends to sleep and at the beginning and end of prayer times — not mean that she should also check at the end of the prayer time, contrary to what you stipulate about the sufficiency of checking only at the beginning of the time?

The text aligns with what we have decided and ruled. It is obligatory for her to check for purity, a "widened obligation," at the beginning of the time. So, she may delay checking and not incur sin by doing so. If she checks at the beginning of the time, her responsibility is discharged. If she does not check until the time becomes narrow, then the obligation becomes "straightened," making it necessary for her to check at the end of the time.