Aena operates free terminal buses between T1, T2, T3 and T4. T4 and T4 Satellite use an automated people mover.
T1–T3 are the close group
Aena states that some T1/T2/T3 movements can also be walked. Do not apply that assumption to T4.
T4 to T4S
The automated people mover runs continuously; Aena lists the ride at about five minutes, but your full transfer includes walking, security/border steps and gate time.
Self-transfer changes everything
If your bags are not checked through, add baggage reclaim, public-side terminal transfer, re-check and security.
Do not confuse T4 with T4S
T4 and the satellite T4S are linked by an automated people mover, while T1–T4 movement uses different airport transfer arrangements. Aena notes that connection time varies by terminal, airline, route and baggage handling. Check the exact suffix on the boarding pass and whether you remain in the protected transfer flow before using a headline terminal-to-terminal time.
Sources and verification
Time-sensitive airport, airline, visa, security and transport details should always be confirmed with the relevant official source before travel.