I just want to let you know that I have been making a Double Fence TaPhSiC shevua for the last few weeks but I never came close to even needing it all that time and I wondered if maybe it was a shevuah levatolo.
Until last Thursday night, when I had a major slip and realized at 1:30 AM on Friday morning that my shevua had expired 30 minutes ago. I quickly made another shevua for another week and went to sleep clean. That Friday night I was feeling very aroused with a mind full of lust and ripe for a full fall, but the thought of having to do the "knas" I set for myself was enough to keep me clean.
So I am going to continue with my TaPhSiC shevuos without doubting that they really are necessary.
Click here for an explanation of the Double-Fence TaPHSiC Method.