A few are a bit awkward at the moment.
Ryanair 230 Zulu can be a s$d if you're in a hurry.
I often feel that the issuing of ICAO 3-letter codes to non airline operators is not helping.
They often have 4 characters after the company code - one example that comes to mind is GBJ ( Global Jet ) and 4 numbers.
And it's usually only a Beech 200 !!