Short answer: pick the 3-10 stores that actually compete for your customer, check their prices, stock, and promotions on a regular schedule (not just when you remember to), and act on changes while they're still recent enough to matter.
Not every Shopify store selling something similar is a real competitor. Start with stores a customer would actually compare you against before buying — similar price point, similar product category, similar audience. Five focused competitors you actually watch beats twenty you glance at once a month.
Checking one or two competitor sites by hand is genuinely fine — a couple of minutes, a couple of times a month, no tooling required. It stops working once you're watching five or more: price changes happen on their schedule, not yours, and by the time you notice a drop during your weekly check-in, a customer may have already bought from them instead of you. The problem isn't effort, it's timing — you find out from a lost sale instead of from data.
You don't need to log in anywhere or access anything private. Shopify stores expose a public product feed that powers their own site search — the same data anyone gets by visiting the store. Tracking tools (ours included) read that public feed on a schedule instead of a person checking it manually.
How often is "enough" depends on how fast your category moves — see how often you should check competitor prices for the reasoning. The short version: fast-moving, promo-heavy categories need same-day visibility; slower categories can get away with less.
Knowing a competitor dropped their price is only useful if you also know roughly what to consider doing about it — match, hold your price and reinforce your value, or wait and watch. A raw feed of price changes without that context just becomes noise you stop reading.
Your Apparel Rivals automates steps 2-6 for a Shopify store — tracking price, stock, promotions, and bestsellers every 4 hours and surfacing a weekly "what to do" digest. Free for your first competitor, no card required.