If this occurs for instance with floating figure number 4, a collision will be reported when the request for floating figure number 5 is encountered; so the respective warning message may be substantially retarded. In fact, the message will tell us that there is a problem with figure 4, but there will be no further hint. So one has to analyze `by hand' that the problem is not caused by collision with figure 5 but with a section heading; even worse: if there is no floating figure 5, one gets no warning message at all.
Furthermore, warning messages will be generated if a Floating Figure
ends in paragraph n and the next one begins with paragraph n + 1.
These warning messages are to be ignored; they are due to some retardation
caused by the \everypar mechanism.