I started to use WinCompose when I changed from a full size keyboard (with numpad) to a TKL keyboard which omits it.
As a mechanical engineer, I often need to type things like the degree symbol and with WinCompose it is just Compose, o, o whereas I used to type these using alt codes.
Other common uses are for sub and super scripts (₁¹), bullets (•), and my own custom ones like on for my email, which I set as Compose, e, m (since these days working from home I am constantly logging into lots of things).
As a mechanical engineer, I often need to type things like the degree symbol and with WinCompose it is just Compose, o, o whereas I used to type these using alt codes.
Other common uses are for sub and super scripts (₁¹), bullets (•), and my own custom ones like on for my email, which I set as Compose, e, m (since these days working from home I am constantly logging into lots of things).