Tazzi 9 to 10 is super squashed as this is the major time slot and everybody aims this slot.. All reality shows like KBC, Dus Ka Dum, Bigg Boss, Khatron Ke Khiladi, etc r squashed in this timing due to which the serials do suffer. Now even Zor Ka Jhatakha in imagine channel is at ths slot..
moreover I don't think Zee wud like to replace PR as t is doing very well at that tym slot...