Puccini almost always handled this better - whether Rodolfo or Mimi or Tosca or Scarpia or Musetta or Mario etc etc, they get to enter, sing for a bit, and finally get to their first big arias after they have had a chance to get their sea legs so to speak.
Not Mario. Look at how little he sings before "Recondita Armonia." ;-) (Also compare with other composers - Verdi, for instance, who has Radames sing his huge and difficult aria right away, etc. It's not as uncommon as you may think.)
Musetta also has very little to sing before "Quando m'en vo," and there are a host of other Puccini characters who disprove this theory (hi, Turandot!)