Will there really be a difference if I apply eyelash serum consistently?

I'm thinking about trying an eyelash serum, but the price difference is bigger than I expected, so I'm hesitating even more.
I'm confused because looking at the reviews, many people say their eyelashes got longer, while others say there wasn't much difference.
I've heard that you have to apply it consistently every day for it to be effective, but I'm worried that I might get lazy in the middle of it.
Since this product is applied especially near the eyes, I'm wondering if it's suitable for people with sensitive skin.
I get eyelash perms frequently, so I'm wondering if I should use a nourishing serum along with them.
I can't easily buy it because I'm afraid I'll just get my hopes up and it will end up sitting neglected on my vanity.
I'm wondering if eyelash serums are products that really make a difference if used consistently.