*My experience is only ordering online.*
This was my second time ordering from Aritzia, and I placed a fairly large order this time around as I was trying to invest in high quality staple pieces that would last a while. One of the items I ordered (Pelli leather shirt jacket) was huge, so I went on the live chat to ask about their exchange policy. I mentioned to the agent that I needed this item for an event so I was concerned the process would take 1-2 weeks. The agent waived the return fee, added priority shipping, and helped me get a new order sent out with the right size. I ended up getting it the next day! This order was also a split shipment, and every package I've gotten from Aritzia has gotten here pretty fast.
I was surprised to see the amount of negative reviews, but then again I worked in retail once and remember people disregarding the return policy and then getting upset the return won't be accepted.