How do natives pronounce the 2nd tone in regular conversation? (Pitch levels: 35, 33, or 434?) In the thread Do tones change at the end of an interrogative sentence?
 , one of the answers asserts:
SCALE KEY: 1 (low) to 5 (high). So 55 is a high level tone, 51 is a falling tone, 35 is rising, etc.

The second tone (textbook 25 or 35) often comes out sounding mid-level
(33) or dipping-rising (434) -- this seems to be especially common at
the end of a sentence.

Is this observation valid/true? If so, why does textbook-Mandarin teach that 2nd tone is 35?
E.g:

XXX很难！XXX is so hard!

Here I understand 很 can be pronounced in a more drawn out/long way so as to stress the severity of hard.

你叫什么名字？What's your name?

Common phrase but 什么 (when spoken fast) sounds a bit like 33 to me.

我想去葡萄牙。I want to go to Portugal.

Pu2tao2ya2 also might be a good example of not completely saying 35 35 35 2nd tones.
I'm very interested in the ability of natives to, on the one hand, abide by the rules of lexical tones in daily speech, while on the other hand,  modify/alter tones for the sake of convenience, pace, brevity, emotion etc. So when I stumbled upon this answer stating that 2nd tone isn't really pronounced 35 and instead is 33 / 434, I immediately wondered if it had any merit.
For sake of context, the same answer also included an observation on 1st tone's 55 modification in daily speech:

The first tone (textbook 55) is always level, but how high it is depends on the level of emphasis. It will be exceptionally high if you want to stress the word: 你喜不喜欢吃..中..餐 &quot;Do you like Chinese food&quot;. It will often sound quite low as the second syllable in a two-syllable word (亚洲 &quot;Asia&quot; ya51 zhou22) and in other contexts where it doesn't need emphasis.
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.