Aspirin is polymorphic, although it was not discovered for over a century due to a lack of research effort.

“So nobody had discovered a polymorph of aspirin, right? So it had been around, it's one of the earliest drugs. It had been crystallized in industry for what, 130, 140 years? And so can you say, "Because nobody had discovered a polymorph of aspirin, therefore..." No. Right? The only problem is I disc”

The number of polymorphs discovered for a compound depends on the level of research effort applied to it.

“The number of polymorphs is proportional to the amount of time and money you spend researching that compound.”