The point in beard growth when the length is beyond stubble or stylishly short fuzz, and a decision must be made to trim, shave, or let it grow.
A secondary characteristic of many beard horizons is, as the length becomes more noticeable, it can become more distracting or annoying...such as with moustache hair that curls over the upper lip, or chin hair that is frequently messed with.
This douchey chinstrap is gettin' kind of burly...think I've hit beard horizon.
Hey, Justin...your carefully cultuvated "fashionably unkempt" party stubble is turning into a full-blown hipster face-wig. I think you blew past beard horizon some time during a weekend PBR bender.