How do natives pronounce the 2nd tone in regular conversation? (Pitch levels: 35, 33, or 434?)
A tone may, upon certain instances, take on a pitch different from its classic pitch. That is to say, while a pitch is absolute (in sound frequency), a tone is not.
中餐 may change from the classic zhōng˥ ˥ cān˥ ˥ to zhōng˥ ˥ cān˧ ˧ when 中 is intended to be stressed by the speaker (not necessarily in a question).
葡萄牙 may change from the classic Pú˧ ˥ táo˧ ˥ yá˧ ˥ to Pú˦ táo˥ yá˧ ˥ in rapid speech. The justification being, a sudden change in pitch requires too much effort. (I used only 1 pitch letter, not more, because they are supposed to be spoken quickly.)
叫他 may change from the classic jiào˥ ˩ tā˥ ˥ to jiào˥ ˩ ta꜌ (i.e., 他 becomes neutral; unaccentuated. In this example, the tone changes too) when the speaker wishes to be imperative with the verb.

Tone sandhi in Mandarin can be classified into facultative (自由音變) and obligate (不自由音變) (Zhang &amp; Yang, 2007:6).* Obligate tone sandhi means it must be followed under all circumstances. The simplest example is obviously two neighbouring third-tones. More difficult examples include the application of neutral tones to distinguish polysemy (see the first point in this answer).

Facultative tone sandhi, however, is optional (that is to say, the classic pitch and the altered pitch coexist, while sharing the exact same meaning, only used in different contexts). The examples 中餐, 葡萄牙, and 叫他 all belong to this category. They are not as well studied, documented, and taught, so much so mastering them would require 'language intuition' (語感).

I actually find it difficult to comprehend how the second tone may take on the pitch ˧ ˧ or ˦ ˧ ˦. The answerer to the original question may a) be attempting to allocate a pitch for a second tone that is neutralised; or b) have thought of a context where facultative tone sandhi is applied. Either way, I cannot think of an example as of now.


Reference: Zhang Bennan &amp; Yang Ruowei (2007). [普通話連讀音變]. Hong Kong: Commercial Press.
* There is no English translation in the reference, so I borrowed the jargons 'facultative' and 'obligate' that are used to classify anaerobes in biology. An obligate anaerobe can only survive in an environment without oxygen, but a facultative anaerobe can survive with or without it.