It can be useful, if you consciously select or follow the thought.
In breath counting meditation for example, we count after each breath, and this is used as a support for active minds to remember they are meditating and track their meditation. Here the count is a thought we follow, but the main focus is on the object of meditation, which is the breath.
Using affirmations ike “I am Love”, “I am one with life”, “I am one with God”, “Everything is God”, “I am God”, “I am Life” in a conscious way, in a way that you choose the words consciously to support your awakening to the most basic truths of life will help. Use words that you are aware of and in alignment with your heart’s knowing to your best knowledge.
If you repeat the thoughts subconsciously, if you aren’t staying present, it will not be effective. For evolution to be able to happen in your understanding, you must be adding your energy to it, meaning you must be coming into your experience as awareness, as consciousness, as life energy.
Remember, this way of using thoughts is just as if you are using a tool. The aim of meditation is to transcend the mind, so do not get unnecessarily attached to the tool. As you transcend the mind to discover yourself as the awareness, as you choose to live from this state more and more, you will also learn to connect with your inner intelligence and the pure energy of life within your spiritual heart. Vice-versa is also true. If you go right for your spiritual heart, or the breath, if you focus on them, you will discover yourself more as the awareness.
When you awaken sufficiently, you will be able to direct your attention without needing to follow a thought. This is your innate ability.