How can the game be made more realistic?

While browsing the spells in Heroes 3, I noticed that many of them are never used. ... Suddenly, spells like "Destructive Ray," "Clone," and "Executioner" would make sense.

Firstly, the value system depends on the situation, and if there are no more valuable spells available, then a destructive ray can be successfully used. Secondly, sometimes only these rarely used spells allow you to win a battle. And thirdly, if there were no bad spells, there would be no good ones either, because everything is known by comparison. And, of course, if all the spells are available, you will always choose the best one (in your opinion), and you will never even try the worst one.
p.s. I recently played a map, and in every battle, I had to use the Executioner spell. And although there were many other spells, it was either impossible to use them (on a dragon) or they were not very useful.