Is the rule that one must partake food only once a day during Mahalaya paksham applicable from commencement of Mahalaya paksham only until the day when one performs Mahalaya paksha tarppanam? Or is it applicable throughout the Mahalaya paksham period?

Those who perform tarppanam on all the 15 days of Mahalaya paksham, must partake food once and partake palaharam for dinner.
Many of us perform tarppanam only one day during the Mahalaya paksham and it is called Sakrun Mahalayam. Melpakkam Swami has averred that such people need not partake palaharm on all 15 days; he also said that they need not partake palaharam even the day before tarppanam day.
Some elders even though they do not perform tarppanam on all 15 days, have a practice of partaking palaharam on all 15 days. Please follow the practice of the respective elders.
As per the learned and wise men, it appears that if one does not perform tarppanam on 15 days, need not partake palaharm on all 15 days.
Palaharam is included in the day of tarppanam and not the day before.