Question

What made the Egyptian lunar calendar difficult to use?

Answer 1

it was difficult to use because every year had different number of days

Answer 2

The Egyptian lunar calendar is difficult to use because every year includes various numbers of days.  

The ancient lunar calendar is the solar calendar that comes with roughly about 365 days per year.

This year included three different seasons of each 120 days, plays the intercalary month of five epagomenal days considered as outside of a proper year. Every season is classified into 4 months of thirty days.