I guess there is a typo of the next here (To the best of my knowledge).
"Within 1 day is going to give you within that next day period, so if you are looking to encompass Monday and Tuesday, you could use 2 days. "
Answer:So within 1 Day is going to give you the same day i.e. Monday whereas Within 2 days is going to give you the Monday and Tuesday.
Btw, what accounts for the next day? Is it 24 hours immediately after the time you visit? or a full 24 hours after the end of the day of your visit?
What I meant was, let's say I visit website A at 2pm Oct 23rd, does within 1 day counts for all the activity until 2pm Oct 24th or the whole of Oct 24th(starting from 12am to 11:59pm)?
Answer: Within 1 Day is referenced from the report suite time zone. so If a visit happens around 11 Pm (Report Suite Time zone and not visitor time zone) on 23rd October then within one day will consists of visits within 23rd October. And within 2 day will consists of the next day.
Link for the AD Hoc Analysis:
https://microsite.omniture.com/t2/help/en_US/dsc/index.html#Ad_Hoc_Analysis_Help
PDF Guide: http://microsite.omniture.com/t2/help/en_US/discover/ad_hoc_analysis.pdf
Let me know if that helps.