After coming back with “Party,” Taeyeon mentions how hard it was to choreograph the dance without Jessica.
Since Jessica’s departure from Girls’ Generation, it has left the members in an even number of eight. Since the girls were used to having an odd number of members for many years, the departure of Jessica has made it more difficult and strange when creating the choreography.
Instead of having only one person in the front who led the team, Girls’ Generation had to get used to the fact that they now need two people in the front at the same time.
Additionally, now that there are less people, the parts of the song must be divided differently in order to fill in the missing parts that were initially suited for Jessica.
Taeyeon mentioned that it was, “Much easier when there was an odd number of members,” hinting at the fact that many things have changed and there has been much to adjust to since Jessica left.
Source: NoCut News