I think the main thing to think about (about these servos) are ---- one method for controlling the shaft-position is by changing a 'pulse width' setting. Eg.... a pulse width of 740 microseconds.
Usually..... 1500 microseconds would correspond to the mid-point position of a SERVO. That might be the '90 degree' position. However, it is just an assumption. But - usually, we assume that 1500 microseconds (general case) corresponds to a 90 degree position.
So 740 microseconds would correspond to some other position. And 2468 microseconds would correspond another position.
The only way we'll know what those exact positions are, will be to "measure" the angles associated with those positions. How to measure? Maybe a rotary encoder of some sort. If we do the angle measurements, then at least we know the relation between pulse width and actual shaft-angle.
Otherwise, if no measurements are done, then the only thing would could do is to 'assume' that the relationship between angle and pulse width is linearly proportional. But we'd only know for sure after angle measurements are done anyway.