SSRS shared data sources and shared schedule
SSRS has a number of configuration files, including RSReportServer.config.  

Both Shared Schedules and Shared Data Sources are good things to create since they help you manage your configuration without giving each and every report it own schedule. View this as saving you some work.  Of course, independent Schedules and Data Sources will likely be needed for some reports.

Since you are concerned with overall load, note that the MaxQueueThreads configuration will control how many parallel reports can run at once.  0 means run as many as possible, but some other number (e.g. 3) will limit Reporting Services to run that number reports at one time.

If you have 10 reports on the same schedule the other reports will run as Queue Threads open up for use.

To configure appropriately need to know your resources available and configure appropriately.  Probably there will be a little trial and error until you get things balanced.