In a drop-in class when one is adjusting a student, is it still possible to be aware of the many? Sometimes yes, sometimes no.
* This will depend on class size, the posture in hand and your own levels of understanding of a pose. For instance it is always possible to be aware of the many when adjusting in corpse, balasana and adho mukha svanasana as observation is always possible as a way of staying engaged with the many. Later on in one’s development as a teacher levels of experience may have grown sufficient to be able to anticipate common difficulties and even at a more experienced level to use more subtle senses to stay both tuned in on the person being adjusted and the rest of the class, these might include anything from a subtler awareness through the ears for instance of the breathing of class members and may even include more subtle senses to including telepathic ones.
* When adjusting, your full attention/absorption is required so you need to make sure that you are in the right space. This is not always possible to tell until you begin an adjustment. An adjustment should not be carried out where the teacher is feeling anger ill will, and should only be conducted from a position of generosity that transcend any thought of generosity.
* What are your motives for adjusting your student: are you motivated by a wish to empower them or yourself? One should not make adjustments to get the student to like you, although getting a student to warm to you may make it possible for them to become receptive to your teachings and this is a valid motivation.