I would say if you judge this particular board most people do not have a signature. *A fair number of the members have a different SOTD every day of the month.
On the other hand I think that with more experienced fragrance users that people definitely have signature notes / houses. *I would definitely put myself in this category.
Also people are always going to have favorite scents to wear on occasions that really matter. *A perfect example of this would be a scent you would wear on a date. *This would be a signature because a lot of time would likely go into deciding which one to wear.