Wind of Change

I think two relatively simple things will bring us much closer to solving the problem.

1. A fixed stage of guild rebuilding, at which control is granted.
That is, neither earlier nor later, but in connection with the critical importance of these spells in the game – at a strictly defined moment. For example.
Town Portal. Requires
in SoD – construction + 3 rebuilds
in HoMM – the seventh spell at level 4.
That is, in both cases, it requires exactly 4 investments in level 4 (the exception in HoMM is the Tower – 3 times plus the Library).
Fly.
Requires 2 investments.
in SoD – construction + 1 (one) rebuild
in HoMM – the second spell at level 5.
Dimension Door.
Requires 4 investments.
in SoD – construction + 3 rebuilds
in HoMM – the fourth spell at level 5.

I immediately suggest paying attention to the fact that two things are described here. The first is the idea itself.
And the second is the decision about the number of rebuilds, which I wrote down, and which I currently consider correct.
And these two things are not the same. If someone is going to respond, please respond to both parts separately.

2. In order to use any spell under any circumstances, the hero must have purchased the book and leveled up the corresponding Wisdom level.
This is necessary to slow down the pace of books, scrolls, and heroes from prisons on Jebus, for example.
In HoMM, Town Portal should not be in the shrines of level 4 at all.