Apart from the economical lunacy of working for nothing on projects, the gamble is not worth it.
I have never known a free-pitch lead to a design consultancy obtaining, at the outset, an account, with an agreed spend over an agreed period, which ad agencies shoot for. Most of the free-pitches are one-off shots.
My other main criticism of free-pitching is that you do not obtain facts, or anywhere near sufficient background, to analyse a company’s objectives, corporate or product, to be able to produce a coherent and conceived answer to support a client’s marketing and sales objectives. You need time to understand, to investigate and research. Most people can only submit “presumed” solutions without any depth of thought.
I have known cases of people winning projects in competition with a company’s main design supplier, but I have never seen the final results that are the same as those presented at the free-pitch.