It is my only means of communicating with people so maybe a day. Not that I talk to everyone that often (well, I do talk to or text the GF everyday), but I don't have a landline at home. I could use the work phone if need be but I'm one of those people that thinks personal calls should not happen on the work phone. And besides, my job actually blocks web-based email so I couldn't get to my Gmail to look up anyone's number. LOL. Jeez...how crazy is that...20 years ago I could've remembered the phone number of anyone I knew...now they'd have to be in my contacts!
I may be an odd-ball here but unless I'm in bed or in the shower the phone might as well be glued to my hip. I don't text or do any FB or other social media on it but it's still a lifeline for me. If for some really strange reason I left home without it, it wouldn't matter how far away I was I would need to drive back and get it if I realized I didn't have it.