I'm a bit confused about the scale of heuristics for implementing A* search. $f(n)$ is the total cost of travelling to a node $n$. It is calculated by $f(n) = g(n) + h(n)$. $g(n)$ is the cost of the path to node $n$ from the source node. $h(n)$ is a heuristic function that estimates the cost of the cheapest path from n to the goal. (Roughly summarised from the wikipedia article on A*)
My question is should $h$ and $g$ be on the same scale? e.g. if g(n) to node n is 10 is it ok if the h(n) is 800?
I've read some conflicting takes on it where one example of using A* for plane routes had $g$ values in the range of 10-50 but $h$ values in the range 100 - 900 but elsewhere I read that they should be the same scale to avoid changing an A* search into a greedy best first search?