St Teresa of Avila said that it is one grace to receive infused contemplation and various other mystical graces and another grace to understand it and be able to explain it in some fashion. In the Catholic Church, God gifted St Teresa of Avila and her collaborator St John of the Cross in their reform of the Carmelite order with an understanding of the ways and graces of the mystical life and infused contemplation like no other saints in the Church. I think you would enjoy reading their works and especially St John of the Cross’s Ascent of Mount Carmel and the Dark Night where you will find what St John treats of infused contemplation is very analogous to what St John Climacus says in your OP concerning sensory images and particular thoughts in prayer. As St John says, through infused contemplation, God gradually purifies the senses both exterior and interior from inordinate attachments to all sense forms and images as well as the intellect or mind from all particular concepts or thoughts so that the soul is as it were in ‘darkness’ to its natural operations and advances to union with God not by a way of knowing, i.e, the natural knowledge we get from using our faculties, but rather by a way of unknowing being led by the Spirit of God.
Both St Teresa of Avila and St John of the Cross teach that one should not leave meditative prayer which as I have said involves using both our rational and sensory faculties such as the imagination before the experience of infused contemplation which God gives to whom he wills and when he wills. St John describes a few signs in a soul of the beginnings of infused contemplation that a person or spiritual director can tell with sufficient probability. Often times the experience in the beginning is imperceptible to the soul and at other times more perceptible depending on God’s will and grace. One of the signs is that a soul does not want to meditate and use its imagination or reason over particular thoughts but it experiences a general and peaceful loving knowledge of God not knowing where it came from but wants to abide in this general or ‘dark’ and peaceful experience. The Ascent of Mount Carmel, Book II, chapters 13,14,15 are very instructive in this regard as well as The Dark Night, Book I, chapters 8,9,10. Check it out, I think you’ll find it quite interesting and I believe these works of St John are online.
One of the reasons why these Carmelite masters of the spiritual life advise to not leave the prayer of meditation which, again, involves our own active use of our faculites before contemplative prayer or infused contemplation is because if we don’t use our faculties in prayer without the experience of infused contemplation, we are virtually doing nothing in prayer. Without the experience of infused contemplation which we can’t acquire by our own efforts but which is a pure supernatural gift from God, most times when we go to prayer we need something to meditate on, think about, read about, or pray about. Of course, there may be times when we just want to sit before the Lord such is in adoration of the Blessed Sacrament as after a day’s work when we are both mentally and physically tired