also print several at once - for small vertical items you need time for the layers to harden properly before the next one is laid down. Otherwise you are trying to lay hot plastic down on soft warm plastic and you just get a mess :-)

Best way is to do several at a time.

Mind you those look like pretty big items - so probably just printing too fast and too hot.

Pet-g does not like to be hurried :-)
Think of it as on rural time rather than city time ;-)