Current definition of MaxTime is:
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[Body]/wsen:Pull/wsen:MaxTime

    This OPTIONAL element (of type xs:duration) indicates the maximum amount of time the initiator is willing to allow the data source to assemble the Pull response. When this element is absent, the data source is not required to limit the amount of time it takes to assemble the Pull response.

    This is useful with data sources that accumulate elements over time and package them into a single Pull response. 
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and at the end of the Pull section it says:
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Upon receipt of a Pull request message, the data source MAY wait as long as it deems necessary (but not longer than the value of the wsen:MaxTime element, if present) to produce a message for delivery to the consumer. The data source MUST recognize the wsen:MaxTime element and return a wsen:TimedOut fault if no elements are available prior to the request message's deadline. 
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This is fairly inconsistent.  The defn of MaxTime has nothing normative in it,
but the paragraph at the end of the Pull section comes really close to saying
something useful.

Proposal:
Move the sentence at the end of the Pull section into the Pull/MaxTime defn:

This OPTIONAL element (of type xs:duration) indicates the maximum amount of time the initiator is willing to allow the data source to assemble the Pull response. When this element is absent, the data source is not required to limit the amount of time it takes to assemble the Pull response. **The data source 
MUST recognize the wsen:MaxTime element and return a wsen:TimedOut fault if no elements are available prior to the request message's deadline. **