I always think it's odd when a pattern says cast-on using the thumb method. I think why?
There are apparently 35 ways to cast-on, so why choose the one that seems the least effective way to produce a neat edge?
It may be looser than other cast-ons, so why not just say cast-on loosely?
Then I learned the long tail method. However, how long does the tail need to be?
When there are lots of sts to cast-on, I found I always ended up with a different number, at least once, out of three counts.
Now I have a fool-proof way of counting, that reduces the stress and time taken.
I cast-on (or chain if I'm crocheting), the first 20 sts and then add a marker, then another 20 sts and add the marker. Each time I double-check the last 20 sts I added, until I have the required number of stitches. Then I only need to count in twenties until I reach the last few stitches.