I allowed this grout to fully dry on an off cut to test Jeff's assertion that it is impossible to remove if allowed to dry on the tile. It came right off of these glossy porcelain tiles using an average razor scraper, as did the grout haze. So it seems that only highly porous tiles are at risk if the grout is left for too long before cleanup, so bear that in mind.

Reference Videos:

1.)Jeff from Home RenoVision DIY:    • This Grouting Mistake will Ruin Your ...  

2.) DIYers Response to Jeff from Home RenoVision DIY:    • My Response to Jeff from Home RenoVis...  

3.) DIYers grouting mistake with Ultracolor:    • How to Avoid a Grouting Mistake - MAP...  

4.) Tile Coach Isaac Ostrom's Grout Performance Video showing the superiority of Mapei Ultracolor:    • WHICH GROUT IS BEST??? Grout Testing ...   (Fast forward to the 37:00 minute mark for results)

Mapei Ultracolor Plus FA Grout Complete Guide Pitfalls Issues Dries Sets Set too fast Disaster Color Variation Color Wrong Color Too Light Blotchy Look Horrible Look Bad Avoid Problems