Taking my house in Downend as an example....
It still makes me laugh that some bean counter at HQ thinks it's a good idea to charge £10 a night to stay there, yet, for those that don't want to pay, they are happy to pay out £16.80 a day in travel expenses.
Why not let people stay for free and save the force some money.

It just seems a bit daft.
I'm not 100% sure on how the courses are run these days, but back when I did mine, it was Friday night, Saturday & Sunday.
If I had to pay for my room at HQ (I didn't), it would have cost me £20. If however I'd have gone home every night, and come back in the morning, it would have cost the force £50.40 in travel expenses. Someone needs to check their maths.