It doesn't appear that standing on a block counts as observing it, so yes. Also don't look back down if you looked away. Which makes it seem more like cartoon physics.
It would be interesting if standing on a block counts as observing certain properties of it, but not others. So standing on dirt means it could change to stone or wood, but not lava or water or make the block disappear.
It would be interesting if standing on a block counts as observing certain properties of it, but not others. So standing on dirt means it could change to stone or wood, but not lava or water or make the block disappear.