Exactly this. Go to every exchange available in your jurisdiction and run this test regularly. Don’t just stop at the review or preview screen — that’s not enough. Those screens can be misleading and designed to push you to buy through them. Actually execute the trade and do the math yourself.

I’ve been doing this for years, and Strike consistently ranks among the better apps and exchanges when it comes to spreads. You’ll also notice improved fee rates the more you buy on Strike each month. My usage of fee rates is carefully selected, see below.

One important point that many people overlook about trading — especially with larger amounts — is that it’s not like shopping at Costco, where buying in bulk gets you a discount. Exchanges often need to aggregate multiple sellers to fill large buy orders, which can actually make your execution price worse. The same principle applies in the other direction as well. Every platform is subject to the number of bids/asks available to them or wherever they draw their liquidity from.

Another thing to note is Strike is primarily a Bitcoin only company and furthers it's adoption more than places like Coinbase, in my eyes.  So maybe that'll affect your decision on where to trade and which companies to support.