Recently, I’ve been dealing with several different logic models which all use the box format. You know the one that Ellen Taylor-Powell advocated in her UWEX tutorial. We are all familiar with this approach. And all know that this approach helps conceptualize a program; identify program theory; and possible outcomes (maybe even world peace). Yet, there is much more that can be done with logic models that isn’t in the tutorial. The tutorial starts us off with this diagram. 
Inputs are what is invested; outputs are what is done; and outcomes are what results/happens. And we assume (you KNOW what assumptions do, right?) that all the inputs lead to all outputs lead to all outcomes, because that is what the arrows show. NOT. One of the best approaches to logic modeling that I’ve seen and learned in the last few years is to make the inputs specific to the outputs and the outputs specific to the outcomes. It IS possible that volunteers are NOT the input you need to have the outcome you desire (change in social conditions); or it may be. OR volunteers will lead to an entirely different outcome–for example, only change in knowledge, not condition. Connecting the resources specifically helps to clarify for program people what is expected with what will be done and with what resources.
Connecting those points with individual arrows and feedback loops (if appropriate) makes sense.
Jonny Morell suggests that these relationships may be 1:1, 1:many, many:1; many:many; and/or be classified by precedence (which he describes as A before B, A & B simultaneously, and agnostic with respect to procedure.) If these relationships exist, and I believe they do, then just filling boxes isn’t a good idea. (If you want to check out his Power Point presentation at the AEA site, you will have to join AEA because access this presentation is in the non-public eLibrary available only to members. However, I was able to copy and include the slide to which I refer (with permission). 
As you can see, it all depends. Depends on the resources, the planned outputs, the desired outcomes. Relationships are key.
And you thought logic models were simple.
