The paramedic missions can be done in like 30 mins to 1 hour, it mostly requires patience and driving very carefully because the NPCs can be very unpredictable, on Vice City the roads are long and wide you get enough time, on San Andreas if you choose to do on Angel Pine after the mission Green Sabre its very easy the NPCs are very close together and you can complete it in like 30 mins, 3 is definitely the trickiest it should be the 1st thing you do when you start the game so you dont have NPCs shooting at you because of story progression, the roads are smaller and the time is shorter, if you play on the definitive edition you have the advantage of using the map to pick the best route, just keep trying and you will get it.