A good signpost is one that points the traveller to the right direction - keeping them on track
But it remains what it is - a signpost, albeit a good one.
The traveller needs it to stay on course but never takes it along or else it ceases to be what it is - a signpost. A good signpost does not follow the traveller either; it points the way and happily bids the traveller farewell.
The traveller reaches their destination and expresses gladness about the sign; the sign in turn is happy to have lent a helping hand and to remain what it is - a signpost.
Happy is that traveller who finds a good signpost and uses it for what it is - a signpost. If their paths cross again, all well and good; but if not, then all well and good.