If I only have one card to shuffle into my deck, can I use Maintenance on the principle of 'do as much as you can'?
In this case, the card specifically prohibits you from using it unless you have two cards to shuffle into your deck.
Source: Furious Fists FAQ (2014-08-28), TPCi Rules Team (2014-08-28)

Relevant cards

Note: All applicable cards may not be listed below.
XY3_96