Yes, I use a secondary for ales generally, except cask ales, which usually get transferred directly from primary before fermentation finishes to condition naturally in cask and when I don't have anything as a secondary available. I have been experimenting with pressure fermentation lagers for about a year without using a secondary. I even left some half batches in primary (corny kegs) on the yeast and served from there, to test some claims. I'm about to change my procedure for lagers and start using a secondary, to see if it makes a difference. I suspect it's going to make a noticeable difference. It does with ales.
Using a secondary is considered good practice generally in the brewing world. Getting the beer off the yeast and giving it time to stabilise before packaging is a key step in the process for many professional brewers and some home brewers. The yeast don't actually "clean up" much post fermentation. They're going dormant with metabolism shutting down. As yeast flocculate the beer starts to clear and taste better. The more it clears the better it tastes. Because yeast taste weird having absorbed and concentrated components of the wort. This is one of the reasons why pros use bright tanks or cylindro-conicals. And why some home brewers use a secondary, the home brew equivalent.
Obviously, home brewers don't need to be as stringent as commercial brewers. It boils down to what we consider acceptable as individuals. Some of my observations. Beers left in primary take longer to stabilise, because residual yeast metabolic activity (bubbles evolving in the yeast slurry erupting) launches trubby yeast trails up through the beer, partially undoing the clearing process. A secondary quickens the clearing process. Beers kegged directly from primary are less stable with the beer served from kegs sometimes changing between pours. I noticed this with all lagers kept on the yeast and served from primary as well as some that were probably transferred to a serving keg too soon.
It's really straightforward to carry out a basic closed transfer from any primary vessel (including a bucket) to a secondary purged of air (O2) using CO2 from fermentation in primary. A little imagination and basic organisation, that's all. Each to their own, though. It's the home brewer's choice, of course. What I find a bit funny, though, is, while a consensus has emerged among home brewers that a secondary isn't necessary and even "risky", conicals have become very popular with home brewers, because they allow home brewers to dump the yeast, turning a primary into a secondary.
