Sample Code:

YourScheduledApexClass obj = new YourScheduledApexClass();

String sch1 = '0 0 * * * ?';
System.schedule('Schedule Job1', sch1, obj);

String sch2 = '0 5 * * * ?';
System.schedule('Schedule Job2', sch2, obj);

String sch3 = '0 10 * * * ?';
System.schedule('Schedule Job3', sch3, obj);

String sch4 = '0 15 * * * ?';
System.schedule('Schedule Job4', sch4, obj);

String sch5 = '0 20 * * * ?';
System.schedule('Schedule Job5', sch5, obj);

String sch6 = '0 25 * * * ?';
System.schedule('Schedule Job6', sch6, obj);

String sch7 = '0 30 * * * ?';
System.schedule('Schedule Job7', sch7, obj);

String sch8 = '0 35 * * * ?';
System.schedule('Schedule Job8', sch8, obj);

String sch9 = '0 40 * * * ?';
System.schedule('Schedule Job9', sch9, obj);

String sch10 = '0 45 * * * ?';
System.schedule('Schedule Job10', sch10, obj);

String sch11 = '0 50 * * * ?';
System.schedule('Schedule Job11', sch11, obj);

String sch12 = '0 55 * * * ?';
System.schedule('Schedule Job12', sch12, obj);

Sample Code:

YourScheduledApexClass obj = new YourScheduledApexClass();

String sch1 = '0 0 * * * ?';
System.schedule('Schedule Job1', sch1, obj);

String sch2 = '0 15 * * * ?';
System.schedule('Schedule Job2', sch2, obj);

String sch3 = '0 30 * * * ?';
System.schedule('Schedule Job3', sch3, obj);

String sch4 = '0 45 * * * ?';
System.schedule('Schedule Job4', sch4, obj);