The phrase "always perceptible" is correct and usable in written English.
It can be used to describe something that is consistently noticeable or detectable in various contexts.
Example: "The subtle changes in her mood were always perceptible to those who knew her well."
Alternatives: "constantly noticeable" or "consistently detectable."
Some of Spiegelman's pages are bound together with visual motifs that are not always perceptible on first viewing.
After the earthquake in L'Aquila in 2009, the earth shook for four years, even though it wasn't always perceptible to people, said Carlo Meletti, the director of the seismic hazard center at the institute.
In fact, though the rhythmic activity can be iceberg-slow and not always perceptible, it is as essential to the music's architecture as the heartbeats of the characters are to the drama.
It's not the lifting and cleaning, the medicines and wipes, and the distant but somehow always perceptible smell of disinfectant.
GPs are often faced with uncertain situations and gut feelings may act as a compass, which is usually active but not always perceptible.
The less dramatic, incremental year-to-year progressions among NBA teams are mostly always less perceptible than seeing a team like the Milwaukee Bucks emerge from the couch of the league (2013-14 record: 15-67) and pull up to the postseason with a top-six seed a year later (2014-15 record: 41-41).
Gesenius et al. (2006): 132) state that, while "[t]he shade of meaning conveyed" by this form "is not always so perceptible", it can be described as being "frequently emphatic".
I tried looking at the glasses, and the eyes, from different angles, and the smile is always there, barely perceptible, but definitely present.
Or will the emptiness of what we lost that day always be somewhat perceptible?
They're constantly in flux, evolving in ways bold and barely perceptible — but always aiming to be in line with that ineffable quality of being cool.
Those repetitions are seldom precise; something — a pitch, a beat — barely perceptible is always added or subtracted.
