Hi Peter..
For a forms list we are showing documents which have their dates within the last 90 days.

I'm not sure how'd you configure this for 20 hours, but I think changing the 90 (90 days) to 1 might allow you to show the last 24 hours for a quick fix.

Here is our filter statement:
[Ticks:Today] - [Date of Recording_UDT_Ticks] < (90) * [Ticks:TicksPerDay]

Hope this helps.. -Jeff

FYI: If you look at the available tokens, this will help with the ticks:
[DateTime:Now]     Current Date and Time
[Ticks:Now]     CPU Tick Count for Current Second
[Ticks:Today]     CPU Tick Count since Midnight
[Ticks:TicksPerDay]     CPU Ticks per Day (for calculations)

Also take a look at the Hidden Columns Reference for getting dates information:
ColumnName     +_UDT_Original     +_UDT_Caption     +_UDT_Value     +_UDT_Ticks          +_UDT_Url
Date                       -                                 -                                 Localized Date    DateTime in Ticks   -
DateTime             -                                  -                                Localized Date     DateTime in Ticks    -

Did it!

[TICKS:NOW]-[Created at_UDT_TICKS] < [Ticks:TicksPerDay] * (.66)  

the (.66) is 18 hours

 For past days

[Ticks:Now] - [Created at_udt_ticks] <= [Ticks:TicksPerDay] * (n) AND [Ticks:Now] - [Created at_udt_ticks] >= [Ticks:TicksPerDay] * (n-1)   

Where n= number of days ago