Most short-term systematic trading I've seen last from a few seconds to within a single trading session.
Anything longer can be called long-term because overnight risk has to be taken into account.
The advantage of short-term systems,
1. can be backtested more vigorously with more results to analyze from
2. lower margin -> higher leverage
3. no overnight risk
The advantage of long-term systems,
1. more tools available (e.g. commitment of traders, open interest, short interest ratio, etc.)
2. lower transaction cost
3. can include complex trading strategies (combination of options, futures, and underlying, etc.)
Both can be very profitable.
Anything longer can be called long-term because overnight risk has to be taken into account.
The advantage of short-term systems,
1. can be backtested more vigorously with more results to analyze from
2. lower margin -> higher leverage
3. no overnight risk
The advantage of long-term systems,
1. more tools available (e.g. commitment of traders, open interest, short interest ratio, etc.)
2. lower transaction cost
3. can include complex trading strategies (combination of options, futures, and underlying, etc.)
Both can be very profitable.