After how many years the design, building blocks, etc. The site is becoming obsolete. For example, now it is new, after how many years will it be old and ugly? Once and for how many years it is necessary to do redesign on the site by changing the architecture, etc. ?
I will not be thrown by links from Google, just copy-paste.
“Sometimes the question is: What is it and why is it necessary? The answer is very simple - website redesign is to change its current design to a new one, in accordance with the latest changes in the field of graphics and in compliance with the customer's corporate style. Site redesign is done to update the site, for example, if the site has long existed by itself, it becomes necessary to change the design of the created site, because There are more and more new sites with modern design, and you cannot fall behind the latest innovations, because everything on the Internet is spreading very quickly and there is a need to constantly monitor these changes.
"Let's say you created your site a long time ago, what do you lose, if you don’t make a redesign, is a decrease in the target audience of the site, because the design greatly affects the influx of visitors, because if the design of the site does not like its end user, it is unlikely to go to him again, because need dynamically changing information. The presence of high-quality design will allow you to compete on this indicator with other sites of similar subjects, which may from a site with a dimmer design lure some amount of network traffic for your site, which will change your position in the search engine results, since by no means the last place in search engines is played by the factor of attendance of a resource.
"Site redesign is necessary for all sites, the only question is in the lifetime and quality of the previous design, basically the lifespan of professional design is about 2-3 years, after which it is recommended to change the site design to make the site more attractive to its users, and for search engines that influence the site’s search engine results.
»Redesign is the same as the design for the site, created either from scratch or using the old style of the site, when only increasing the quality of images, videos and screensavers on the site is done, but the main point is the first item. For the site, first, an assessment is made whether it is worth altering the current design at all, after which a new layout is developed, after which, after its approval, the information from the “old” site is transferred to the updated one.
"Usually companies notice that it’s time to change the website design when the website loses its audience, the amount of sales of goods or the provision of services decreases, i.e. customers that this site sends to you and there is an urgent need to change something. It is not necessary to postpone the redesign of the site indefinitely, if you consider that your site has lost its former popularity and quality.
Just imagine such a situation - you meet a girl (well, or in a guy, depending on your gender and tastes) ... you love her, appreciate her and all that ... But then suddenly you slap yourself on the head and say: "Uh you have been meeting for two whole years already ... it's time to leave .. no, I, of course, love her and all that, but still for two years, that's enough already ".... Somehow unnatural, isn't it ? Most likely, you will part with her for some other, more objective reasons, and not because "two years already." I hope you understand the analogy?
In a couple of years. But seriously, this question has no exact answer.
It can be said for sure that the conditional “gap” between site redesigns will be somewhat reduced in the foreseeable future.
To change the internal structure (for example, from table to div) is up to you, IMHO it should be as up-to-date as possible at the time of creation.
Regarding design, there is a concept as a corporate identity. And any project that has taken place should follow it. You can imagine that the well-known VK will radically change the design. Noise from the users will be mass.
Changes on work projects need to be made occasionally, users are frightened people.
It is impossible to measure the time interval of the design change.