(a) A watcher serving at a central counting station may be present at any time the station is open for the purpose of processing or preparing to process election results and until the election officers complete their duties at the station. The watcher may serve during the hours the watcher chooses, except as provided by Subsection (b).
(b) A watcher may not leave during voting hours on election day without the presiding judge's permission if the counting of ballots at the central counting station has begun.