One of the things I have always maintained is that one reason old people get less done is not exhaustion, although that happens. It is that vision starts to go to hell in a handbasket. Can you say presbyopia? Reading glasses? argh.
So... my young followers, do not make small tables with 6pt font. I cannot read them. I will resent having to work extra hard, and strain my eyes to see your table/figure because you are so hell bent on packing stuff into your proposal that there is no room for this critical figure except to be read with a magnifying device (be it analog and handheld, or digital on the computer). Let me add that the worst is when I blow up your figure on my computer and it looks like it was done with crayons.
One guideline for using figures is when the words it takes to explain the image take up more space than the image. Sometimes you need the raw data to prove you can do it. But sometimes you can describe a figure, succinctly and you are wasting space with it. Some diagrams help explain the design, the equipment, a particular relationship. But lots of time they don't. Get someone else to look at those beloved babies of yours and give you some honest feedback.
I've never ever seen a Specific Aims that was improved by including a figure. It may exist. It may be your proposal. But what does need to be in the SA is sufficiently dense and important, that taking the space for a figure, a graph or a table on that page usually is not a good idea. And for heaven's sake, do not put in a quasi-table of definitions. There should not be 10 or even 5 things you need to define in your SA's. If there is one use a clause such as: Bunny Transfiguration, a developmental change that occurs at 6 months of age, turns tadpole bunnies into fully hopping creatures.