I have found that using Oil Flo and a non-scratch scouring brush works ok, but its still hard work which requires a lot of elbow grease.
What I normally do, is scrub the tape residue with the scourer first, then soak with Oil-Flo and follow up again with the scourer and scraper if needed.
If you are working in a team, it is better, you get the first person to go along with the scourer while the next guy follows with the Oil-Flo, when the first has finshed a side, he then wfp or trads the glass off.
Repeat this and it's soon done.
Charge well over the top for the job.