Default Problem mit roms to install aps

I think that problem is whit all roms which canīt install aps after one time because real internal memory must have same space free though roms supports ext2in and thatīs whay you could not install after one time more apps thoug you have enough internal memory.Problem is when you install aps i donīt know whay bat all from aps donīt movs in ext partition thoug she internall memory is and when real internal memory is 0mb then you could not install more apps and some wont work because she have no space for cache or eg.Sorry for bad english.