By working with a fitter, (s)he can help you with that determination. Which wedge you carry comes into play as well. Deloft the 8-P or increase the loft in the 5-7’s? The other possibility is to leave the lofts alone.
I’m not a T100 level golfer. In my case, the wider gap between my T200 7 (29.5 degrees) iron and the T350 6 iron (25 degrees) maintains the 5mph increase in ball speed and descent angle of the 7 iron. My next club is a 23 hybrid, as it adds the requisite 5 mph ball speed, height, a descent angle from the 6 iron. Without the “ideal” 4 degrees in loft separation.
The focus is on keeping 5mph more while maintaining height and descent angle. The loft is only adjusted to meet the shot making.
If you can maintain the 3 keys through the 5 iron T100 , then you don’t need a mixed set, unless the T150 works as your 4 iron.