I think a 25' depth might be more limiting than people realize. Yes, most performance stages are rectangular, but they are also generally much larger for established companies-- Lincoln Center, for instance, is 80' x 100'. Skating rinks are rectangular but an Olympic rink is 98' x 197' and it is considered good, even necessary, practice to use diagonals for many things. Sure few variations or dance solos take the whole stage, but if we want to compare to spaces that allow for wide artistic movement, 25' can be very shallow and 40' depth will easily be used. I'm almost certain athletes would use the diagonals for tumbling anyways. They will fill and overfill any amount of space allotted them.