why not simply "roll with the (life) punches", i.e. as though unfolding events are themselves omens?
I think there's a lot of value in this. For starters, and this has happened to me, one can end up over-relying on divinatory devices to make sense of what life throws your way. The more you do it, the less it seems to give those kinds of abundantly clear answers for which they have an uncanny ability to provide.
On a more fundamental level, I think these divinatory devices are ultimately a crutch of sorts. Like glasses for what could be described as "etheric astigmatism". Ideally, one should be able to see all that divinatory systems reveal without the need for such devices, instead just reading it from the events of life itself. Of course, this goes beyond mere intellectual understanding of the events and their cause-effect relationships.
A good example may be Plum-Blossom numerology for the I Ching, which takes on the (chinese) calendaric marks at the moment in question to construct a hexagram for the moment, which then goes on to give the divination for an action to be taken. Same with horary astrology. As you can probably guess, these all rely on somewhat arbitrary interpretations and significations on specific times that construct a sort of system that allows one to work out, synthetically, a symbol or set thereof from which to derive a "divination", a more or less educated guess on the currents underpinning a moment or action. Back to I Ching, ultimately what counts and underlies the whole system is the interplay of yin and yang tendencies in the different aspects of our environment and ourselves, such as the season, the state of the moon, the time of the day, etc. Ultimately, they are also bound to the imposition of the diviner of yin-ness or yang-ness on a chosen phenomenon of observation, phenomena which is also somewhat arbitrarily chosen by the diviner. Before going into materialist-rationalistic objections on this practice, one must not forget the very modern discoveries by which the observer plays a crucial role in influencing the turn of events merely by the act of looking and interpreting. Thus, divinatory systems are a sort of peek into the "schrodinger box" of our fates!
How does one come to certainty about whether a given device is reliable, versus imagining it is? Is faith involved? If so, wouldn't any device sufficiently believed in work/"work"?