Letter sampler with embroidered heart flanked by the initials P.I

How many hours would it have taken to make this sampler with its thousands of minute cross-stitches?
This cloth has been embroidered with a multitude of letters in different shapes and sizes, some of them plain, others) quite ornate. Note the heart on the left, with the P on one side, and the I on the other – the maker’s initials.
During needlework classes at school, girls practised the skill of marking by making so-called samplers. The patterns could be letters or small motifs such as a flower, a windmill or a tree of life. Marking the family linens with one’s own, personal mark served to make them recognizable when after laundering the items were laid out on the common bleachfield to dry.