i've had mine for a month and they still hide.i had them in their own tank for a few weeks, then moved them to the 55 g and they still hide.the male is getting used to me now, a bit anyways.
mine are out in the open but i guess thats cuz they were the first ones ever to be in the tank...also i think mine were happy to be out of that crowded tank at petsmart and were checking out the place...
I have heard new platies doing this...mine....on the other hand...are nosey little buggers....they follow me as I walk past the tank....they all come to the front when I watch them...they supervise me feeding the bnose plecs...they supervise the gravel vac when I clean....they like a "spa" at water change time and are always ready to eat....they have bene like that since I got them...even the newer platies. Its a pain when I change the water as they like to go into the gravel vac tube.
Its funny too...the fry from them....are nosey too...perhaps its genetic