Squashing more sections (rectangles) in would not look good, because they are pixel-aligned and squashing would blur them together.
We could conceivably add more sections at the end, but given the best heat sink is more than 2x as good as the standard one, it would double the size of the GUI 
Alternatively, we could halve the number of sections for the standard heat sink, meaning that it would only take up 50% of the space. I don’t like this solution either because for most players the HUD would be half-empty