A teacher from Xi’an recently told me that “wo3” (“I”) and “ni3” (“you”) are special and don’t have their tones changed to 2nd tone when followed by another 3rd tone. She was quite adamant about it, and very quick to catch this tone change each time I made it. I’ve never heard of this in my life, and no one’s ever brought this up regarding my pronunciation. In fact, I find two consecutive low-pitched 3rd tones a bit vocally difficult. Paying close attention to her pronunciation, I heard her saying “wo3” and “ni3” as full 3rd tones so that the tone bends upward before following 3rd tones, which is comfortable to do.
Do people have experience with this? Do your spoken “wo3” and “ni3” undergo normal tone sandhi, or are they always full 3rd tone when followed by another 3rd tone?