Generally there is no "fixed distance" as it depends on the location. You need to capture as much or few needed to correctly reflect the look and feel of the location.
However, Google has a recommendation if you are planning on using their Auto connect feature:
"Space the photos about two small steps apart (1 m / 3 ft) when indoors and five steps apart (3 m / 10 ft) when outdoors."
More details here: https://support.google.com/maps/answer/7012050?hl=en&ref_topic=6275604