It seems reasonable to assume that the calendar mentioned is for exactly twelve months. Such a calendar will usually have 52 Thursdays, but will have 53 when
a) the first day of the calendar is a Thursday, and
b) the second day of the calendar is a Thursday and the calendar includes 29 February (which of course occurs only in a leap year).
In both these cases the last day of the calendar is a Thursday, except when (a) is true and the calendar contains 29 February; then the last day will be a Friday
Every day of the week could be subject to precisely the same analysis.
53 in the maximum.
there are 53 or 54 thursdays in an year depending on the day which year starts
53 Thursday can occur
For any given level n there will be a maximum of 2n nodes.