Most websites are commissioned like a building: agree the scope, construct it, hand over the keys, done. It is a comfortable model. It is also the reason so many businesses find themselves rebuilding every three years and wondering where the money went.
The site stops matching the business almost immediately
Your website describes the business as it was understood on the day the content was signed off.
Then you add a service. Drop one that was not profitable. Start pursuing larger clients. Win a project worth showing off. Hire someone whose expertise changes what you can sell.
None of that reaches the website, because reaching the website requires somebody whose job it is to put it there. Six months in, the site is describing a slightly different company. Two years in, it is actively working against you — pulling in enquiries for work you no longer want and staying silent about the work you do.
Nobody owns the part that matters
Almost all of the commercial value of a website is decided after launch: which pages bring in enquiries, which ones lose people, what customers actually search for, which services deserve more space.
The build-and-handover model puts a full stop exactly where that work should start. The agency's obligation ends at delivery. Yours begins, except you were never given the tools, the time, or the information to do it.
So nothing happens. Not through negligence — through structure.
Rebuilding is the expensive way to improve
The usual outcome is that three years pass, the site is visibly tired, and someone proposes a rebuild.
A rebuild is not just costly. It discards what you learned. Every insight about which pages converted and which enquiries were worth having is thrown away with the old site, and the new one starts from assumptions again.
Continuous improvement is nearly always cheaper over the same period, and it compounds instead of resetting.
A better question to ask a supplier
Not "how much does a website cost".
Ask: who is responsible for this still working in eighteen months, and what does that cost?
If the honest answer is "you are", that is fine — as long as you know it going in, and have budgeted for the person who will do it. What causes damage is assuming somebody is watching when nobody is.