Clean up table space

We have a primary-standby (10g database) system in our production environment.  I am planning to run two scripts to release spaces in a table that  has been heavily cleaned up by 'delete ..' statement.

"alter table .. shrink space compact' and  (may or many not) run "alter table .. shrink space '

 I am testing the script in a single database server(non-standby based) and it took over an hour to finish.  I wonder if there is a concern I need to address when I run it in the production environment of the primary server which has three standbys assoicated with it.