prescribed number of pradakshinams

कुंभिवक्त्रे रवौ गङ्गाधरे विष्णौ च शास्तरि
षण्मुखे सुंभसूदिन्यां वृक्षराजेप्ययं विधिः॥
kuṁbhivaktre ravau gaṅgādhare viṣṇau ca śāstari
ṣaṇmukhe suṁbhasūdinyāṁ vṛikṣarājepyayaṁ vidhiḥ||

And this is about the number of Pradakshinams we are expected to perfrom in respect of each deity
Ganesha.. the elephant headed God One
The Sun God Surya                       Two
Lord Shiva the Gangadhara         Three
Lord Vishnu                                   Four
Lord Sastaa.. Ayyappa                  Five
Lord Shanmugha..Subramania    Six
The Divine Mother (the slayer of
Sumbha)                                          Seven
The Lord of Trees, the Ashwatha
or the Banyan tree                         Seven

This is a widely held custom.. in Kerala.. The practices will vary.. In some temples there is only half Pradakshinam for Shiva..