That depends on the scale. A couple jobs ago we had enough objects that an 80-bit key wouldn't have had a low enough collision rate (better models of computation for that domain include sqrt/cube-root ideas to account for information propagation in physical space). Sometimes you have to use more constrained devices so that your max effective constant-time word size (for the same computational cost -- not to quite be confused with the CPU's "native" word size, whatever that means in your circumstances) is 8, 16 or 32 bits (or, most recently at my last job, for _reasons_, 11 bits), making even quite small tables not quite O(1).

Many compsci researchers like the word-ram model of computation to avoid a bunch of extraneous log factors and to apply exactly the intuition you're describing, so that hashtables are actually O(1). That's not a bad habit. It introduces extra log factors in other places though, so I think it's a bit of a wash, and given that it doesn't model the actual register machines we use it feels a bit intellectually dishonest to me.