Merlin, Merlin, Merlin; another couch (nearly) subjected to needless abuse, man o man, there are way too many of those. If the care of your sofa is so difficult and you are unable to give it proper housing conditions I will gladly adopt it and give it a good home...
Seriously though,
Even with muscular legs of an ig the leash is not like that for a dog. You can't really hold back or stop a determined adult lizard, but you can use it to slow them down. I use one like a tail extension where the lead is made of birght colored string (say 10 meters / 30 feet worth) so I have something to look for and lead me to my ig. In the case where a lizard takes off up a tree a leash will be of no help.