Ignoring the revolting pedant I use them when racing. There comes a point when after prolonged effort I can’t eat normal food. They are quick and easy to eat.
Normally buy a box of 24 in spring and that’ll last me a year.
Don’t use them on normal riding although I often put one in my camelbak in case someone is really struggling.
They do help, the energy boost is noticeable but short lived (30 minutes?). The caffeine ones work as well but caffeine in that forms seems to make me feel sick so I avoid them. Stay off all other caffeine for a few weeks and it is really noticeable.
For general riding normal, cheaper food is fine and is what I use.