I got a cardboard box, lined the inside with aluminum foil and put some little wire racks in it. Put shoes, phones, credit cards, etc. on the racks and the UVC hangs above the box. Downstairs spare bedroom, close the door.
I’m not so sure how well the aluminum foil works to reflect the light and get the bottoms of the items on the racks, so I turn them over. I’m not sure how long they need to be hit with (25 watt bulb) but I figure 20 minutes each side should be good.
Except for the shoes - after they get the UVC I squirt the soles with 409 and let sit for 5 to 10 minutes or more (I’ve read some people say 30 seconds is enough and others say 4 minutes.) And then I use soapy water and a brush to finish cleaning the soles.
All the stuff I go through to leave the house and come back really cuts down on the errands!
The inverse-square law applies; so, 20 minutes should be more than enough. I think 20 minutes would be enough for (say) an 8'X8’X8’ room. If you have a large box (say) 4'X4’X4’ that would imply you only need 5 minutes. Given that the light only works where it shines, you might consider running it for 10 minutes, then moving everything around and giving it another 10 minutes. Your aluminum foil reflectors would give you a big margin of safety.
Don’t forget the mail... and any cash you get from the bank or ATM... and your purse.