Torque.. When you loose a T Chain will the piston hit the valves on a savage ???

This is kinda scary and apparently not that unusual.  So I guess you need to replace that chain every 20K or so?  Can't remember if there's some recommendation in the manual.  Auto timing chains seem to last well over 100K.  I read somewhere a single stresses the chain more because of the uneven rotational pulses working on just two lobes, unlike a multicylinder engine where this gets evened out.