Tacking angle versus wind speed.
Another big factor affecting the closest sailing angle to the true wind, is simply the wind strength.
On the diagram below I have played around with wind speed and boat speed vectors for my own Ingeborg..
This is the constant factor: Ingeborg points about 32-33° from the apparent wind, as indicated on the wind indicator. She does so in any wind speed on flat water. I have added a couple of degrees leeway in the diagram, so the apparent wind is set to just below 35°.
In 7 knots true wind, she may touch 4.0kts.
In 14kts true wind, she may touch 5.0kts.
These are not accurate numbers, but they are still realistic.
As can be seen on the diagram, where the wind strength (wind from north) is 7 and 14 kts, is that Ingeborg sails a lot closer to the true wind in stronger winds, but still outside 45°.
My guess is therefore that it will take perfect conditions and an America's Cup helmsman to consistently tack Ingeborg inside 90°
Arne

(Get better resolution in Arne's sketches section 8 diagram 32)
Edit:
At 7kts wind , the tacking angle is thus 108 degrees and the VMG only 2.35kts.
At 14kts wind, the tacking angle shrinks to 93 degrees and the VMG climbs to 3.44kts.