Box plot generator built with Next.js 14 + Chart.js - 4 hour build time

Challenge: Build and ship a functional web app in 4 hours.

Result: Box plot maker with CSV upload

Stack:

Next.js 14 (App Router)

Chart.js + box plot plugin

Tailwind CSS

Vercel

Time breakdown:

Hour 1: Setup + core logic

Hour 2: UI components

Hour 3: Content + SEO

Hour 4: Testing + deployDocument format comparison

Link: https://boxplotmaker.online

Question for webdev community:
For simple tools like this, do you think 4-hour sprints are sustainable? Or am I cutting too many corners?