Survey frequency on MetroOpinion mainly depends on how well your profile matches advertiser target groups, so incomplete or outdated profiles reduce invites significantly.
The platform itself states that providing detailed demographics, interests, and updating changes helps you qualify for more surveys.
You should also log in daily and check your dashboard, because new surveys are added regularly and some never get emailed. Being active increases visibility and chances to catch surveys before they fill up.
Responding quickly to invitations matters more than most users think, since surveys are sent to many people and close once quotas are filled. If you ignore or delay, invites may shift to more active users.
This is the information we have, but if you have more insights from your experience, please share in the comments.