When describing activities that are done during daylight hours, "by day" is a common phrase used. However, there are several synonyms that can be used interchangeably to add variety and creativity to your writing. "During daylight hours" is a straightforward alternative, while "daylight" is a succinct option. "In daylight" and "by sunlight" also work, emphasizing the natural light of the sun. Other possible choices include "during the day," "throughout the day," and "in the daytime." Depending on the context, you may also consider "during business hours," "working hours," or "regular hours." Experimenting with synonyms can keep your writing fresh and engaging.