Session length, and the hour most guests underbook
Sessions run from one hour to a full eight hour night, and a quiet guest who cannot decide is usually better served by ninety minutes than by an hour.
The ladder is straightforward. Read it as rungs: the hour, the ninety minutes, two hours, three, and past the third each further hour costs whatever the first one did. Add a second pair of hands and the hourly line doubles; add a second guest who shares her and it doubles by the same measure; give each of two guests their own therapist and it sits at four times the lone hour. The euro amounts live on the women's own pages, and this glossary keeps out of them. A full night is covered under overnight.
Why the hour is often the wrong choice here
An hour is a real booking and plenty of guests are right to take it. But a guest who has asked for a slow tempo and little conversation is buying unhurriedness, and an hour has a shape to it that works against that: by the time the room has properly settled, roughly twenty minutes in, a third of it has gone. Ninety minutes is where the tempo stops being something either of you is managing.
Reading the extra half hour as money
Stretching sixty minutes to ninety adds a half hour's worth of her rate, and stretching ninety to a hundred and twenty adds an identical slice. Judged against the evening it changes, the first of those two steps buys considerably more than the second. Beyond two hours the character of the booking changes again rather than simply lengthening, which is a different decision and not a matter of getting more of the same.
Deciding without a conversation
If you cannot settle it, name the two lengths you are choosing between in the thread and take the longer one. Nobody is talked upwards here. The length is written down once, it sets the figure, and a booking already agreed can be shortened by a line sent before she leaves, which simply makes it a shorter booking at the shorter figure.