My gecko, Gecko Joe Exotic, only ever comes out of his coconut hide 1 every 2 days for food and water and to strech his legs a little bit. His tank is 30cm by 50cm he doesnt use most of it would it be OK to downsize.
I'm assuming you have a leopard gecko. You already have him in the equivalent of a 10 gallon tank, which most people feel is on the small side for a leopard gecko. He's nocturnal, so, unless you have a webcam on him all night or you stay up all night and watch him, you don't necessarily know what he's doing during the night. Consequently I recommend you leave him in this enclosure size (or, believe it or not, even consider upgrading to a 20 gallon which would be 30x75cm
I do stay up late most night and sometimes he weights in his hide for food and once at his glass doors. I have already asked this fourm if there is something wrong with him, he got impacted several months ago and then he was not, but before then he was very active and now he is not. He is in a ten gallon because he is only 7 months old I was going to upgrade his tank in June ,when he would be one, but then I didnt know if I should upgrade or even downsize the space he doesnt use.
It would be great to see a picture of your gecko (I looked at the original thread but didn't see a picture). I had a gecko for more than 10 years who hid all the time, to the point where I named her "Cameo" because she only made cameo appearances. Some of them are just really reclusive. Still, I don't recommend going smaller than the size you have.