When we do this we make use of the SQL option > Edit Query to include all the robots in group then drag it into the Maint schedule. Its much easier once you have a SQL query template that can just accept the names of all the robots or the IP's you want to include.
Example:
select * from CM_COMPUTER_SYSTEM where name like ('%robota1%')
or name like ('%robotb2%')
or name like ('%robotc3%')
or name like ('%robotd11%')