tim> show configuration applications | display set | match junos-tcp
set applications application junos-tcp-any term t1 inactivity-timeout never
# commit confirmed will be rolled back in 2 minutes
Just need to make sure that you apply the inactivity-timeout under the term t1 as this is how the default group is configured.
But yes from my experience you would need to define the timeout value for all applications used in the security policies.