Just recently stumbled upon this puzzle so still might not understand something. Regularly I find myself in the situation when I cannot deduct concrete number anywhere on the field and, as a result, I just guess some number and continue to solve the puzzle looking if everything is ok or I move to dead-end. If dead-end then I return to the position before guessing and make another guessing.
It isn’t fun.
Am I doing something wrong or guessing is indeed a part of the puzzle solving?
Try not to guess. It usually just leads to more trouble. Only really ok if you get out down to two numbers and can backtrack if your wrong.