General sales ups and downs

Hi guys question about general sales and numbers…
seems that you get a number you can sell each day that amazon wont let you get over…or is this just me
i sell well no major issues ,have seen slow sales if i get a negative feedback for few days or a return etc…
so…
you guys that have been on here longer its seems like you need perfect scores no negative anything to do well

oh and then there is advertising that i have tried but is a waste of money