Model max length not set. Default value

Hello, im just curious about the value of model_max_length in some tokenizer configs.
Some model have a value, e.g.: all T5-based models have a model_max_length of 512.
In some models (e.g.: MBZUAI/bactrian-x-llama-13b-merged) there is no value set but the default VERY_LARGE_INTEGER.

Do some tokenizers have no limit? Did the authors “forget” to enter the value?
How can someone find out what the maximum length is?

Same Doubt here. Can we get an expert’s or enthusiast take on the matter ?