That's not how LLMs work. These filler word tokens eat petaflops of compute and don't buy time for it to think.
Unless they're doing some crazy speculative sampling pipeline where the smaller LLM is trained to generate filler words while instructing the pipeline to temporarily ignore the speculative predictions and generate full predictions from the larger LLM. That would be insane.
If however there were a way to keep passing hidden states to future autoregressive steps and not just the final tokens from the previous step, that might give the model true "thinking" time.
The layout of the NN is actually quite complex, which a large amount of information calculate beside the token-themselves, and the weights (think "latent vectors").
I recommend the 3b1b youtube-series on the topic.
https://arxiv.org/abs/2501.19393
These tokens DO extend the thinking time. We are talking about causal autoregressive language models, and so these tokens can be used to guide the generation.
This is not the case -- it's actually the opposite. The more of these tokens it generates, the more thinking time it gets (very much like humans going "ummm" all the time.) (Loosely speaking) every token generated is an iteration through the model, updating (and refining) the KV cache state and further extending the context.
If you look at how post-training works for logical questions, the preferred answers are front-loaded with "thinking tokens" -- they consistently perform better. So, if the question is "what is 1 + 1?", they're post-trained to prefer "1 + 1 is 2" as opposed to just "2".