I just did a 350 item job which was really 416 at a grocery store. 3/4 of the items had a regular price, a loyalty price, and an expiration date that needed to be entered. It took 9.5 hours broken into three visits. That said, I don't foresee you having nearly so hard a time at a pet store (unless they have a lot loyalty prices or special promo prices).
What I learned is to really go through your missions when you are finally allowed access (like the day before). Go through the lists and see how they have them categorized. I lost a lot of time because while some items were grouped (you could stay in one aisle or close) but then at the end of the mission would be the "Uncategorized" items which had me running from bread to baby food (again!) and back to frozen food - all for only one or two items each.
Use the skip function to scroll through to prevent leaving one area to go elsewhere to then have to return to where you just were,
Be sure to have a fully charged battery if you think your phone can't handle at least 3 solid hours of work. Also be prepared to see "Uh oh! That price is outside of our range. Can you check again?" Sometimes it's because you mistyped something , or it's the wrong item (check SKU number)which is a good thing, but sometimes you typed what's there and it doesn't like it. Sometimes you must take a photo.
Good luck and I'd love to hear how it goes.