Measured: Adjustability is counted in separate tension points: zero on a slip-on, one per strap or buckle, and one per eyelet pair on a lace-up.
The basics
What to know about closure type
How a shoe fastens sets how much of the fit you can change after the box is open. A lace-up gives you a separate tension point at every pair of eyelets. Slip-ons give you none, so the size on the label has to be exactly right. Between those poles, zips trade adjustment for speed, buckles adjust in fixed steps, elastic accommodates without any action from you, and hook-and-loop adjusts fastest of all.
Judge a closure on three questions. How many points of adjustment does it give, and where do they sit: instep, ankle or shaft? How fast is entry, which matters daily for boots and for anyone with limited reach or grip? And does the mechanism actually work, since buckles and laces on fashion shoes are often sewn-down decoration over a hidden zip or elastic panel.
Failure modes differ too. Laces fray and cost a dollar to replace. A broken zip usually means a repair shop. Elastic relaxes over years and cannot be tightened again. That repair picture is worth weighing on any boot you intend to keep for a decade.