yes you can, but it will make your character a little bit slower than using shift to run This is why the biggest part of the runners don't use it and it is not mentioned in the rules
edit : that's false, check tendog's response for more details
The only time loss from using Auto Run is from the time spent turning it on. You won't move any slower/faster than if you held shift/x during the entire run.
Actually I double checked, Auto Run might actually save a very slight amount of time during the run?? Auto Run apparently doesn't work the same as just running, in any case
About a month ago, there was a community poll held in the discord to add IGT to Deltarune. After a close poll of about 70 to 5, we have added the use of IGT to the game. This IGT only makes a difference to the All Chapters categories, removing the time spent switching between chapter 1 and chapter 2