A 4:1 MUX can be built by using three 2:1 MUX. But I've not done it this way: I've used a 2:4 decoder to make a 4:1 MUX. Does it matter?
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It matters depending on what you optimise for. Your way is probably better once you factor in the extra cost a higher part count causes, and the fact that a single chip solution is likely to be faster than one involving 3. For most purposes, there isn't too much of a difference. Though, I will note that your schematic and actual application are important pieces of information required to pass specific judgement.