Your sanitizing solution only needs to be in contact with the walls of whatever you are sanitizing for about 1 minute. So by swirling the solution around every minute or so for about 5 minutes should be more than enough time. Or you can agitate the solution for about a minute continuously or use a rag saoked in solution and wipe the walls down for a minute or so.
I agree with Kavos no need to use 6 gallons in a 6 gallon bucket / carboy or whatever.
A gallon in a 6 gallon carboy should be more than enough.
Here a web page on Iodophor.