T.I.T.S. is the preffered, profeesional failsafe method. this not only gives back up, but if the duality is set at opposing angles, more stability when using a power cutting device around thin threads that support your life.
i don't necessarily use the backup with a handsaw. Another stabilizing technique for either or, is to throw lanyard under what you are standing on so it returns to opposite side/hand; tighten up with bent knees, then stragihten legs to get the opposing, stabilizng forces of the lock. This doesn't even route much of the force of the equal and opposites seeking each other thru your back to strain it, but back should still be straight.
Run the drill; if it takes tooo long, ya ain't done it enough to have it polished!