It is not possible to say with 100% accuracy how often a horse might race in any one year or over the course of its career.
In general, Standardbred Horses can race weekly however every horse needs rest and potential time for injury however we would look for horses to generally race 25+ times in a year that is not impacted by injury. Standardbred Horses are not affected by weather and race year-round even in winter climates of northern part of North America.
Thoroughbred horses on the other hand race much less because racing is more demanding on them and require more rest between races. You will likely see a Thoroughbred race 9 to 10 times a year..
Weather has a huge impact on the ability of Thoroughbreds to race and particularly winter.
This is one of the reasons we decided to start Two Breeds so our owners can enjoy our horses racing year-round.