Rather than creating a whole bunch of small timetable arrays, could you instead use a timerange to select the appropriate subset of the rows of the timetable each time you need one of those "new" timetable arrays?
Or depending on what you want to do with the new arrays, perhaps some combination of retime, rowfun, and/or the various data preprocessing functions that accept timetable arrays (functions like groupsummary, movmean, etc.) would let you perform your operations on the various sections all at once.
