Zen is very hard. Specially without a great teacher. A popular idea is that Zen could "get away" from emphasis on study because it produced great teachers who did not "need" to refer to scriptures -- when they could simply refer their disciples to reality, using whatever means (including Buddha's words).
This Zen attitude is believed to come from many things. One of them is it's origin in the flower sermon. Another is the culture it developed around accusing exclusive intellectual/abstract understanding of the dhamma -- carried out famously by the "finger and the moon" metaphor. Like a person who spends his/her life studying sex but no amount of study got him/her close to lose the virginity.
But shikantaza has a flip side of the coin that is as devoid of value as studying Buddhism for Buddhism sake (if nibbāna is of concern). And that is, by "just sitting", it's quite possible one's life is spent "just sitting" and nothing really happens, ever. Like drawing lines and random symbols on a canvas and hoping to arrive at language and poetry.
In my understanding, the critical point is: in a learning process of any kind, there must be an evaluation process (ad-hoc, implicit, explicit, formal,... whatever), done by yourself, your teacher, or both (when one has a teacher). And evaluation is always a function of one's goal and one's current distance to that goal. It's evaluation that tells where you ware, if you are moving, and towards what you ware moving. Otherwise, it's just random walking around and hoping to stumble on a goal that became a taboo(*) to acknowledge.
(*) it seems every once in a while this idea becomes popular: that "enlightenment" is not something to strive for. What was once a pedagogical instruction towards specific people overly attached to a goal keeping them from progress, is now a full doctrine.
On a final note: the major risk of not reading the Buddha's word is, years later, find out that what you were doing had little to do with what he proposed.