I make custom impulse responses frequently or think about them when I'm gathering field recordings. Traditionally IRs in audio reverbs were used to model rooms or vintage gear etc, so it is my go to fx for making sounds feel more natural.
One way to think about IRs is that each individual sample in your IR will time shift and scale your input. So for example, you can make custom delays by just putting in taps which I like to do for dub type pads. This one has a low pass filter automated over to give a bit more life.
The output of convolution is only the frequencies contained in both the IR and the input. Another type of IR I use frequently is taking very noisey or distorted sounds (so with the full frequency spectrum) which will smear the input over a long time. I do this when I sample a fraction of a note(s) that I want to make pads out of.