Position sizing answers one question: how much of the book should ride on this one trade? It's separate from, and arguably more important than, the entry/exit signal itself. A great strategy with reckless sizing can ruin an account; a mediocre strategy with disciplined sizing usually just underperforms.
Common approaches range from a fixed dollar amount per trade, to a fixed percentage of capital, to volatility-based sizing (risking less on a wild coin, more on a calm one, see ATR), to formal frameworks like the Kelly criterion.
zengtrade caps every paper position notional and layers portfolio-level limits on top through the Risk Governor: per-symbol exposure, sector/category concentration (so "all altcoins" doesn't quietly become one correlated bet), and a crowding cap on how many strategies can hold the same name at once.
Educational content, not investment advice. zengtrade is paper-first and non-custodial.