Hi Slicepong,
Firstly I would say it’s fine to use a slightly closed bat for flicks for sure, as long as you make sure to hit through the ball woth confidence.
On your point regarding the half long balls you can play both a flick or a push if you realise the ball isn’t going to come off the end. As you mentioned it can be good to experiment with not using a push at all to get you in an attacking mindset, however sometimes once the ball has dropped lower after being prepared for a topspin and then having to change your shot a push or touch is an easier option to execute well.
Also as you mentioned this decision making does improve with experience, so practice these situations and see if you can still flick well on these half long balls and if not make sure your practice switching to a push or touch too.
