Yeah, 1 in 60 simply put means if you are one mile off track at 60 miles = 1 degree off track. we used to use a rule of thumb where by say you are halfway up your 40 mile leg (so 20 miles in) and you were 1 mile off track, 60/20 = 3 so multiply your track error by 3 = 3 degrees off track.
To be honest its a bit of a faff, Standard closing angle, or double track error are much more effective ways of regaining track. Or if you are anything like me, IE a complete lazy git who likes to keep the workload to an absolute minimum. Draw five degree drift lines either side of your planned nav route, then you can work out quickly and easily how many degrees you are off and indeed how much you have to turn to get back on track!... probably not the best explanation but hey!
Tacho.