Phaedrus—I'm interested in your answers to these questions, too.
I have long been somewhat mystified by the
spend time V-ing construction and its variants, of which
waste time V-ing is one, and have not, until rather recently, come upon any analysis that could compete with the one TheParser has given. The alternative analysis that I have come upon is given by Hendrik de Smet in
this paper and one chapter of his book
Spreading Patterns: Diffusional Change in the English System of Complementation (2013).
In those two texts, De Smet discusses what he calls Integrated Participle Clauses (IPCs), which he differentiates from adverbial (adjunct) participle clauses and some other constructions. The category of the IPC is not a box that holds everything nice and neatly, however. De Smet discusses a gradient between the IPC and related constructions, and, sadly, it so happens that the
spend/waste time V-ing construction is located somewhere along the borderland.
I have not yet thought carefully enough about IPCs to explicate de Smet's analysis, let alone to take a stand on what the
spend/waste time V-ing construction really is. I will say, though, that I think TheParser's gerund analysis seems to work very well for the sentence at hand, in which the V-ing phrase does not need an overtly expressed subject at all. Indeed, the sentence could be rewritten like this:
Most of the time is wasted in the doing of unnecessary things.
At the same time, the gerund analysis might be seen to have a drawback, in that, if the gerund phrase (with its preposition undeleted) is moved to the front of the sentence, it does seem to dangle:
?? In doing unnecessary things, most of the time is wasted. The V-ing phrase seems to me, independently of de Smet's treatment (which I am still wrapping my head around), to be unseverable from
waste time.
Another drawback is that, in other cases where the preposition
in takes a gerund object, it can't necessarily be deleted. While I think
waste money V-ing works much like
waste time V-ing, what about in a predicate like
waste water?
The city wasted water in letting the water-slide park remain open year-round. Could we delete
in in that case? I'm not sure:
? The city wasted water letting the water-slide park remain open year-round.