Is it optional to voice the final letter and linking sound?

I am learning English and I like to observe how people say it.

Most of time, I hear "but I" as "buttai", "out of" as "outtof." In this case, the T is pronounced.

However, I also hear when people say "they don't exist", it sounds more like "don nexist" or "they don Exist"(with a clear E sound). The T is silent.

Recently, I heard a movie character say "They won't make it out alive", and it sounds like "They won makkittou alive". There are few things I observed,

1. The T from "won't" is silent,
2. The K sound "make" links to "it", and T sound from "it" links to "out"
3. The T sound from "out" is silent and doesn't link to "alive", I can clearly hear "alive", not "talive".

So I am very confused about when I should pronounce the final letter, and when I should link it.

I learned from both American and British films, but the example line is from an American TV show.

Solution 1:

The final consonants usually are being pronounced, but through some allomorphs that make them harder to hear.

• "but I": In this case the /t/ is being pronounced as either a flap or a glottal stop.
• "out of": The /t/ will be pronounced as either a flap or maybe an unaspirated consonant /t/.
• "don't exist": The tongue is in the same place for /n/ and /t/. You could say that the /t/ isn't being pronounced, or that it's being assimilated into the /n/, which is more dominant.

• "won't make": this is different from the "don't exist" - the 'n' can easily flow directly into the /e/, but it can't flow into an /m/. I think in this example the /t/ is bring pronounced, but as an unreleased stop.

  A stop consonant is one where the entire vocal tract gets blocked, so that no air can pass through. Making a stop produces two sounds: the sound of blocking the air and of unblocking it. In many words or phrases a series of two stops get joined together so that the blocking of one is pronounced followed by the unblocking of the other. You can hear this in the word doctor. You pronounce the blocking of the /k/, the tongue moves while still blocking the air completely, and then you release the air as a /t/.

  In this example the /t/ is being released as a glottal stop.

• "make it": the /k/ is definitely being pronounced, but as an unaspirated consonant, so that it sounds somewhat like a /g/.

• "out alive": like "out of", this will be pronounced as an unaspirated /t/ or a flap.