The reason why it takes time to warm up your voice

Does it take you a lot of time to warm-up your voice? Ten to twenty minutes is the average length of time it takes most people. The voice needs to warm-up. A warm-up is commonly done before singers sing in a performance, or in advance for public speakers who use their voices for long periods of time. If you take too long to warm-up your voice prior to a vocal performance, the reason is probably because you are doing too many exercises or the exercise are too long in length. Breathing, stretching, drinking, and a run through of the scales from low to high are just some examples. If you take a lot of time to warm-up your voice before singing, your muscles may become too hard around the throat area. Specifically if you warm-up your voice for more than one hour, the throat will definitely be tired before you even start singing or speaking.
Vocalization is operated by the movements of the musculus extrinsic laryngis. You don’t need extreme muscle strength to produce a loud voice, because the volume of the voice is not proportional to the momentum of the musculus extrinsic laryngis.
The 5 factors of Creating Voice

Note1:If you get tired to sing a song really early after starting, your musculus extrinsic laryngis might be hard. The reason why is low or poor blood circulation due to the stiffened muscles. If you have poor blood flow to the muscles relevant to vocalizing, then enough oxygen and nutrition will not be carried or delivered to those muscles.
The lesser horn of the cartilage is more than likely pressured due to LDP (larynx deep position) when opening the glottis, causing air to leak and making it hard to control the voice. Dry vocal mucosa also contributes to this status, resulting in having a problem with falsettos. Proper density and moisture of the throat from the vocal mucosa is necessary, so always be aware if your throat is dry when you are singing. Muscle power is being used every time the glottis opens and closes, and excessively doing this action too much during a warm-up will cause the muscles to tire around throat easily. When you warm-up, warm-up slowly and in moderation. Even the slightest form of excessiveness when warming up can result in negative changes to your sound and throat muscles.