Do you typically pursue EMG/nerve conduction study in patients who already have a clinical diagnosis of myasthenia gravis?

Depends on antibody status. If the patient is antibody positive (AchR or Musk) and has a classic presentation (e.g., Fatigable ocular and or bulbar weakness) and good response to first or second-line treatment (pyridostigmine, prednisone) then it’s probably not necessary. Seronegative patients or those with atypical presentations and poor response to treatment must get electrophysiologic testing to confirm diagnosis (RNS or SFEMG). I have had cases of ptosis and/or diplopia appearing fatigable on exam, who ended up with an alternative diagnosis (like aponeurotic ptosis, late decompensated congenital strabismus, or even progressive external ophthalmoplegia) after electrical studies turned out negative for MG.