Manual winding is not a limitation: it is a constructive choice that eliminates the rotor and everything it entails. Without the oscillating mass, the movement can be thinner, lighter, often more visible. The De Bethune DB2517 and the La Joux-Perret D100 and D101 calibres exist in the sizes they do precisely because of this absence. The rotor, when present, takes up space and adds weight; removing it, however, means making a pact with whoever wears the watch.
The mechanism is simple in logic: by turning the crown, energy is transmitted to the mainspring through a system of gears. When the spring is fully wound, you must stop. In modern movements there is almost always a safety mechanism against overcharging, but in vintage pieces — an AS1475 by A. Schild, an Excelsior Park EP40, a Seagull ST1901 — it is advisable to proceed with caution. I have restored enough broken springs to have learned prudence.
Frequency affects the winding experience. A calibre that beats at 2.5 Hz, like certain low-frequency movements of German tradition, returns to the crown a different resistance than a modern 4 Hz. The slower beat is felt even under your fingers. It is not nostalgia: it is physics. Same thing for power reserve: a manual movement well proportioned to the barrel can reach 48, 60, even 80 hours. The Ressence Type 11 eliminated the crown by replacing it with a lever hinged on the case back, solving the ergonomic problem without changing the principle.
In terms of finishing, the absence of the rotor exposes the bridges integrally. This is where manufacturers invest: Armin Strom hand-polishes the bridges of the ASB19 calibre, Vacheron Constantin applies ten different decorative techniques to the Calibre 978. It is not decoration for its own sake: when the movement is visible, every flaw is visible. Manual winding forces you to do things properly.
The hack function — the seconds hand stop when the crown is pulled — is present in most contemporary manual calibres and in many restored ones. It allows synchronization to the second with an external reference. In vintage movements it is not taken for granted: check before buying.