verilog-minimum-comment-distance

verilog-minimum-comment-distance is a variable defined in `verilog-mode.el'.
Its value is

10

• This variable is safe as a file local variable if its value
  satisfies the predicate `integerp'.

Documentation:
Minimum distance (in lines) between begin and end required before a comment.
Setting this variable to zero results in every end acquiring a comment; the
default avoids too many redundant comments in tight quarters.

You can customize this variable.