What would sports commentators and reporters, not to mention drama and film critics, do without this and other words to use metaphorically. No doubt those settings do give rise to lots of nail-biting. After all they are usually sedentary activities when the mind is fully engaged and the hands, which are normally active, have nothing to do but the harm done in these instances would probably be at the less serious end of the nail-biting spectrum.
However records might show that nail-biting habits grew more prevalent with the advance of labour-saving devices in and around the home (less work for restless hands) but even more so with the advent of screens particularly screens in the home. The habit gets relative free reign when attention, that of the biter and everyone else, is focused elsewhere. It is after all a private and secretive indulgence.
It is hardly surprising then particularly in the case of the habit among adults that there is so much embarrassment surrounding it and not a popular subject of conversation or debate.
Online discussion and support groups are however a great step forward for those engaged in them which are mainly women. The anonymity offered by the internet also offers both sexes access to solutions not hitherto known to them. Having found those solutions they can hope to enjoy those dramatic cliffhanging endings without having to survey the more personal wreckage, ie. their bitten nails, at the end.