It was kind of your parties fault though.
1 they did not secure the windows, so a lock pick could not open them.
2 they all took separate rooms in a town that was not very secure.
3 they posted the guards poorly.
4 they did not buy extra rooms and leave them empty
5 they did not spell protect things, the party was 2x the level of thieves from what i skimmed.
I could see it working if they were in their own building, but guards should be hired for that reason. The party was simply careless.
If you don't like the mechanic then house rule it as a non-critical it is a option.
