There is no specific regulation with regard to the time between azan and iqamah for any obligatory salah. This is something left to people to decide based to their circumstances which may differ from one community to another and from one situation to the other. However, it is generally recommended that a reasonable amount of time be considered for people to perform ablution and observe Sunnah Prayers.
This applies to all the five obligatory prayers with no exception. Those who take care of masajid (i., mosques) should consider circumstances of its attendees without following whimsical considerations.