just to make sure that my assumption is correct:
I have a Next button and for that interaction (click) the Time spent per visit (or visitor for that matter) metric shows 4 seconds.
My hypothesis is that it takes 4 seconds after this event before the next event is recorded (page view of the next page).
Can someone confirm my interpretation?
Typically time spent per visit relies on the session based part of a visit on a page(s) its correlated against pages. The action of a click is typically event or instance based.
Can you supply an edited screen grab of report your are looking at?
From the help docs:
Time spent per visit (Seconds)
Total seconds spent / (visit-bounces)
Represents the average amount of time visitors interact with a specific dimension item during each visit.
Average time spent on site (Seconds)
Represents the total amount of time visitors interact with a specific dimension item, per sequence with a dimension item. It is not just limited to “site” averages as the name suggests. See How Time Spent is Calculated section for more information on sequences.
Note: This metric will very likely differ from Time Spent per Visit at a dimension item level due to the differences in the denominator in the calculation.
How does Average Time Spent on Site differ fromTime Spent per Visit ?
The difference is the denominator in the metric:
As a result, these metrics may yield similar results at a visit level, but will be different at a hit level.
Your hypothesis would only be correct for 'Time Spent per Visit', if users only have one sequence per dimension item within the visit. Otherwise it looks like 'Average time spent on site' is the metric to align with your interpretation.