It depends on the scent and the medium really. When I worked with ocelots we used scent pads(squares of synthetic carpet) to enhance our camera trapping and would refresh the scent bi-weekly on average. It seemed to me eventually the cats would lose interest once a site was visited a few times and no longer novel so that might be something else to consider. They would still visit occasionally but would spend less time there and visit less frequently.

It is possible to mix the scent with an oil based medium like petroleum jelly (vaseline) to make it last longer, although this would depend on the composition of the scent used.

Thank you for your responses! Were the scents changed every now and then to somewhat retain the novelty of the site? Also with the scent pads, would you just get a piece of synthetic carpet, and coat it with your scent and then place it by your camera trap?

Thank you

Really it was just in hopes that a stronger smell might keep their interest. We would attach the pad to either a wooden stake and place it between two cameras (to capture both sides of the cat) or nail it to a tree trunk. The cats responded to a variety of scents including the Weaver scent mentioned in Weaver et al. I don't believe that scent is available anymore, that Weaver stopped producing it. That is second hand information though. Various perfumes work just as well though.

We had good success with both of the scents we tried: catnip and men's obsession.....yes, the cologne for humans!!  (as far as I know ours is the only paper that compares this scent to other attractors, however they are many anecdotal notes in popular media about the use of this scent for cat surveys).   You can find the paper here in researchgate:https://www.researchgate.net/publication/229980652_HairTrap_Efficacy_for_Detecting_Mammalian_Carnivores_in_the_Tropics?ev=prf_pub

We were using nail and velcro carpet squares.  We would put the scent on the carpet surface and leave those in place for long periods of time (access to the transects was very difficult).   So, we did not replenish at all and still had good results.   To me it was amazing that after a couple of months the obsession carpets still had some smell detectable by us!!   But as you can read in this paper we found no differences between these two scents.

I agree that cats get likely attracted to this as a "novelty" scent in their territories.  It would be interesting to find out if any other men commercial fragance also draws them.  I also assume they might lose interest over time.   So, instead of scent renewing I would suggest putting a new set of hair-traps (parallel locations maybe?) with different scents.  But then you face the issue of comparability and replication.

I will go against constant visits to a hair trap station as every visit will bring human odor to the site.  Aversion to the scent can be very strong and this might be the reason cats stop using heavily a station.   Most people do not take great care to handle and set up these stations.   I have even seen people smoking while preparing these hair traps!!!  You should wear gloves while building them, use an odor remover and pack them in thick zipper bags.  In the field we de-scent (commercial product used by hunters), use rubber boots, cotton gloves and only ONE person sets the station.   Need to have the mindset of a trapper.  If you know a person with those skills get some advice from them.   Hope this helps.

Article Hair‐Trap Efficacy for Detecting Mammalian Carnivores in the Tropics