Complex sentence: As a result of many regional ampitheatres having their annual "summer concert" series, Fox-scheduling for the warmer season started slowly, with very few bookings; more were added during July, for dates through October.
Split into simpler sentences: As a result of many regional ampitheatres having their annual "summer concert" series, Fox-scheduling for the warmer season started slowly, with very few bookings. More were added during July, for dates through October.