You don't even need unusual architectures - e.g. it's pretty easy to find a constant that might be fast to encode a value as 2 immediate and store the value in memory as two halfword stores on ARM - see https://alisdair.mcdiarmid.org/arm-immediate-value-encoding/ for the immediate encoding. It might be quicker than loading those immediates into a register, shifting and or-ing them as necessary, and then doing a single store. Especially if your focus is on code size (for small platforms or cache utilization reasons).

An I wouldn't be surprised if there's some weird x86 encoding that in some cases helps code size similarly, with different encoded instruction lengths allowing for different immediate sizes.