I don't think the between option is available but you can pass the exact time or day etc the syntax are available as examples here:
https://github.com/javan/whenever
And for your task may be you can pass a array of time:
every :day, :at => (1..15).to_a.map{ |x| (0..55).step(5).to_a.map{ |a| ["#{x}:#{a}"] } }.flatten do
# Run rake task.
end
# => ["1:0", "1:5", "1:10", "1:15", "1:20", "1:25", "1:30", "1:35", "1:40", "1:45", "1:50", "1:55", "2:0", "2:5", "2:10", "2:15", "2:20", "2:25", "2:30", "2:35", "2:40", "2:45", "2:50", "2:55", "3:0", "3:5", "3:10", "3:15", "3:20", "3:25", "3:30", "3:35", "3:40", "3:45", "3:50", "3:55", "4:0", "4:5", "4:10", "4:15", "4:20", "4:25", "4:30", "4:35", "4:40", "4:45", "4:50"...]
This is just a example. You can make it as you desire. And I am not sure if whenever
accepts time in 24 hour format or not. So please check it out and try like this.
Update 1:
Was doing more R&D and found the above to be the solution to the problem as denoted by the gem creator. Here is the link:
https://github.com/javan/whenever/issues/506
Didn't knew about rjust
which can be added above. And regarding AM & PM I think you will be needing to add that (not sure). If it needs to be added break it into two. One for AM and other for PM.
Update 2:
Another easy solution I Found is:
every '*/30 6-9 * * *' do
runner "Model.method"
end
The above runs in every 30 minutes between 6 to 9.
Source:
Rails Execute Cron Job or Rake task for specific time period
Hope this helps.