Similar results for my workflow. And the Round art comes out significantly less round without prompt changes (more input tokens)

  Setting (1024x1024)   Tokens   Cost/image   Time
  2.5 medium              439     $0.014     12.0 s
  2.6 low                 824     $0.025      6.7 s
  2.6 medium            1,449     $0.044      7.9 s
  2.6 high              1,758     $0.053      8.9 s