what is the longest period of time...

[se7en]

... that you've had a ball python on the loose before you found him/her?

I had one missing for a day and half before I found him coiled up in the inner workings of the back of my fridge.

[bcr229]

I had a Brazilian rainbow boa go AWOL for three weeks. I found him getting a drink from a bowl of water I'd put on the floor of the snake room.

[Albert Clark]

My pastel garter who was gravid went missing for about two weeks. After searching relentlessly for about 1 week she came out from under a radiator in the bedroom. I tried to catch her and she jetted under the tv console and wouldn't come out until I placed a thawed fuzzy on a paper plate and watched her eat it. Then I grabbed her. Of course she had the babies while out of the enclosure. We actually found 5 babies at different times and locations over the following weeks.