The below sentences are from one website. (The URL is also below.)
http://www.petsmart.com/uc/petarticles_db.jsp?ucCategory=ARTICLE&ucTopic=CAT&ucSubTopic=GROOMING&ucSubTopic2=&ucContent=/articles/content/dog_cat/fleas/solutions/6909.html People think that fleas spend
most their time on animals, but they don't. They leap, feed, and leave and spend
most of their time in the carpets, couches, and floors.
The sentences have inconsistencies in the connection between "most" and "their time." The former connects two phrases without "of" and the latter with "of."
I checked out "Practical English Usage," and I found out examples of a connection of some determiners with noun phrases without "of," such as,
? all (of) his ideas
? both (of) my parents
? half (of) her income
but any examples of a connection of "most" with noun phrases without "of."
However, googling shows "most their time" can be possible, if not inconsistent, in this context.
What do you think of my argument?