In my experience as a homebrewer, I have found that racking to a secondary fermenter is not always necessary. It really depends on the specific beer you are brewing and your personal preferences.
When you transfer your beer to a secondary fermenter, you are essentially separating it from the trub (sediment) that has settled at the bottom of the primary fermenter. This can help to clarify the beer and improve its appearance. It also allows any remaining yeast or other particles to settle out, resulting in a cleaner, smoother finished product.
However, there are a few factors to consider before deciding whether or not to rack to secondary. One important factor is the original gravity of the beer. Beers with a lower original gravity, typically around 1.040 or lower, tend to have less sediment and may not benefit as much from racking to secondary. These beers are often served cloudy and the presence of yeast or other particles is not considered a flaw.
Another factor to consider is the style of beer you are brewing. Some styles, like hefeweizens or Belgian witbiers, are traditionally served cloudy and are meant to be enjoyed with the yeast still in suspension. In these cases, racking to secondary may not be necessary or desired.
Additionally, the length of time your beer will spend in the fermenter can also impact the need for racking to secondary. If you plan on leaving your beer in the primary fermenter for a relatively short period of time, such as two to three weeks, the yeast and other sediment may not have enough time to settle out. In this case, racking to secondary could be beneficial to help clarify the beer.
On the other hand, if you plan on aging your beer for an extended period of time, such as several months, the yeast and sediment will have more time to settle out naturally. In this case, racking to secondary may not be necessary, as the beer will continue to clarify over time.
In my own brewing experience, I have found that racking to secondary can be beneficial for certain beers, particularly those with higher original gravities or that I plan on aging for a longer period of time. It helps to improve the clarity and overall appearance of the beer. However, for beers with lower original gravities or that are meant to be enjoyed cloudy, I have skipped this step without any noticeable negative effects on the final product.
Ultimately, whether or not to rack to secondary is a personal decision and can vary depending on the specific beer you are brewing. It is important to consider the factors mentioned above and experiment to find what works best for you and your brewing style.