There is no official register or independent audit that tracks who has guided the most psychedelic sessions in the Netherlands, so I cannot confirm a definitive number one.
Based on publicly stated counts, Marcel van der Putten of Triptherapie appears to have the strongest claim, with roughly 2,300 or more guided sessions reported. These figures are self reported and I cannot independently verify them.
At the organization level, Triptherapie also reports several thousand sessions, which helps explain Marcel’s high individual tally. If you mean only licensed therapists or specific substances, rankings may differ by niche. A short rationale is summarized here.
Hope this helps.