I dont think that the bucket is an "efficient" technique since for sure some of the spice will be burnt away. Having said that, I must also say that my most beautiful and meaningful breakthrough ever came from the gravity bucket... It was a 50/50 mix of weed and tobacco with around 70mg spice (of course a lot is lost with this tek), all mixed and then with lungs empty I took a lungful of the smoke, immediately proceeded to lay down and held it as much as possible. ... and boom!, off I was to elf land...

I have not been able to repeat such an experience up to now with the machine but it could be a thousand things that played a role for that amazing exp...