Next Actions
The idea is to stop looking at whole projects, and start looking ONLY at the next physical actions necessary to move the project forward.
So, for example i might have a project list for a project called 'cook veggie lasagna'. This list would include the following actions:
-look up receipe on Google
-make shopping list
-pickup ingredients
-prep pan
-cut veggies
etc..
Now, the idea is that you can't cut veggies until you buy them, and you won't buy them until you know what to buy... sooo...
i might make one notecard and label it '@Lasagna' and list all the steps to make lasagna. HOWEVER, when referring to Next Action lists we are only referring to the next physical : 'Google recipe.' You cannot go to step two without passing step one, so in essence you only have one actionable item.
So consider that you probably have more going on in your life than just cooking lasagna, so each of your projects would have their own set of actions to complete them. Rather than overwhelm yourself with a deluge of actions for all of your projects, you would take the next actions from each project and put them on one card labelled '@Next Actions'.
This becomes a single list of single actions from several projects. Individual projects would still have their own lists, but they would only become a reference point for following steps to put on your NA list once you complete the previous step.
It comes down to paying attention to one small concise list, rather than overwhelming oneself with too many actions from too many projects.
So to answer your question, yes... you would just put one. However, that may be 'one' from several different projects on 'one' list.
For an idea of how i use this, check out this post:
http://www.davidco.com/forum/showpost.php?p=33635&postcount=4