No. This is incorrect – It is only coincidentally true this year.
Pentecost is not an “anchor feast” except in so far as it is the last day of the Easter Season. Ordinary time resumes on the succeeding Monday and by coincidence this year, resumed with the 9th week of Ordinary time (which is week I of the Psalter).
Next year, Pentecost will fall on 20-May-2018, and Ordinary time will resume on Monday 21-May-2018 with week 7 (Psalter week III). The following year, Pentecost will fall on 9-Jun-2019, Ordinary Time will resume on Monday 10-Jun-2018 with week 10 (Psalter week II).
What
do act as “anchors” of a sort are the first Sundays in each Season: Advent, Ordinary Time, Lent, Easter – The first Sunday of each Season indicates week I of the Psalter (NB that Lent begins on a Wednesday – that and the succeeding days until Sunday are assigned to week IV of the Psalter).
To figure out the week of Ordinary Time after Pentecost, count backwards from the last week, which is of necessity week 34, and which kind of explains why a week of Ordinary Time often goes missing around the Lent/Easter time. This year it did not (we went from week 8 to week 9), but eg last year we went from week 5 to 7 with no week 6.
Or, liturgical books frequently have a table to summarize these data – Here is a handy example from the Bishops of England and Wales
liturgyoffice.org.uk/Calendar/Info/moveable.shtml
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Armchair Liturgical Calendar Nerd