Well, there are different bots for different purposes.
A bot operated to post advert messages might want to post them on high profile accounts.
A bot for a "500 followers for $5" company might be more likely to follow low-profile accounts, with some random activity/follows thrown in as camouflage.
A bot operated to amplify certain messages/opinions might follow accounts of middling visibility, and focus on likes rather than more visible activity.
A bot operated to post advert messages might want to post them on high profile accounts.
A bot for a "500 followers for $5" company might be more likely to follow low-profile accounts, with some random activity/follows thrown in as camouflage.
A bot operated to amplify certain messages/opinions might follow accounts of middling visibility, and focus on likes rather than more visible activity.