" No mention of having another party behind them to pick up the...

" No mention of having another party behind them to pick up the rig if BYE decide to drill only one well."

eg, The current operator cancels their slot due to delayed permitting,
BYE take the rig early,
Previous operator get their permits while BYE drills the first well, hence would take the rig back after BYE's first well if circumstances made that advantageous for BYE.

just one of many scenarios wrt rig timing and rig slot options depending on how things play out.