For older orgs, one may have Apex classes at V27 or earlier. Such classes were allowed to also include testmethods.

Gearset's Monitoring job ignores these test methods leading to a false sense of security that one's org is "correct"

Example class is at V24

class Foo {
void doStuff() {}
static void testmethod myTest() {
new Foo().doStuff();
System.assert(...);
}

The myTest will not be run by Gearset Unit Test Monitoring. It will be run by Setup > Apex Test Execution > Foo > Run tests