Let’s take this basic example:
mew
<span style="font-size:; display: block; text-transform: uppercase;"><span style="font-size:; display: block; background-color: red;">mew</span></span>
Notice how I used two when I could’ve used just one? Those types of situations, basically. Use as many spans as you need to, but don’t overcomplicate the design by using too many when you don’t need to use a span for every separate property-value pair.