Let us assume for the basis of this discussion that when the student, who has delayed progress of his/her thesis, later wishes to continue it, the adviser has to pick-up where he/she left off and re-engage with the student and his/her thesis topic. By that time, the adviser will have researched thesis topics with other advisees and may have lost his/her own motivation to continue with the recalcitrant student. If the advisor drops the it may student take some time for the advisee to find another suitable and willing supervisor. If the adviser continues on with his former advisee he/she will have to dredge up the student's earlier work and re-engage with the literature and the student's work which carries a substantial burden of effort with it.