It can't be quantified, but there are a number of ways you find out when the limit has been reached:

* The petition for divorce appears on the breakfast table.

* The garage key is forever missing and never to be found.

* You arrive home one evening just in time to see the Salvation Army truck pulling away from your house — and the garage door is open.

* All your bicycles are stacked in a neat piles of 7 deep around the sofa; there's a note that conveys the message that you will more enjoy sleeping here with them than upstairs with me!

* Your former nightmares are replaced by a succession of horrifying images of scored, bindled, irreplaceable bearing races and cones.

... to mention a few