Muslims of one neighborhood gather five times in the neighborhood small mosque, every day.
Muslims of one locality (i.e. multiple neighborhoods) gather once a week in the biggest mosque of locality on friday noon.
Muslims of one city gather twice a year on Eid festivals in the big grounds or big mosques.
Muslims of the world gather once a year on Hajj in Mecca, Saudi Arabia.
You see, Islam doesn’t explicitly tells Muslims of any one country to gather, because Islam marks nationalities on the basis of faith, not on borders. Muslims all over the world are one nation.