Like you, I usually cut everything first. unless there is a challenging part in a block. I have been well known to make a sample block to make sure I have my measurements correct. Just recently I did it twice where I cut strips incorrectly and got so frustrated I could scream. By the time I decided to make my sample block I discovered why the cuts I was making were wrong. So I can do the same quilt with smaller sizes or do something entirely different with the strips I cut and could not use for the quilt top I made. If I have to figure the sizing myself I make the sample block. If I am using an established pattern I will cut everything first to be sure I have everything I need correctly.