I'm a big believer that one should be blind-fold familiar with one's aircraft. I'm also a big believer that one should take as much time as one needs to accomplish each phase of the flight.
On fire flights, many times we tried to be within five minutes from dispatch to wheels in the air. Sometimes a little longer for loading and any ground delays. That means being completely preflighted and ready to go, first thing in the morning. Flight gear hanging on the side of the airplane and cockpit flows made getting airborne to be a quick process. Everything was done on the go.
Preflights shouldn't be rushed. Neither should before start, after start, taxi, or before takeoff checklists. Take the time you need. Being familar with the airplane and the procedures helps a lot. One can shorten the time required by doing flows in the cockpit and around the airplane. Doing things in a logical order, as a flow pattern, doing all the checks, then consulting a checklist to ensure everything was accomplished, makes things go faster.
I like checklists done out loud, and done as challenge and respose. I do the full checklist, out loud, even when flying alone.
I'm a big believer that if a checklist or flow is interrupted, it should be done again, started from the beginning. Too easy to pick up again at the wrong point and miss something. Start over.
Don't rush warm-up times. Don't be in such a big hurry that you miss the point of the checks that are being done. During the mag check, for example, don't just note an RPM drop; let it stabilize, note the value, and note the smoothness or roughness of the working mag. During a carb heat check, don't just look for a drop, but give it fifteen seconds or so; make sure that any ice that's present gets melted, check for roughness. When cycling the propeller, let it cycle, if the manufacturer approves or allows; don't just pull it back and slam it forward again. Do it several times; get warm oil in the propeller.
With time and experience, some things can be done on the fly, moving. Doing mag checks while holding the brakes is nonsensical, but sometimes in the case of a long, straight taxiway, the checks can be done while moving. When flying to rough fields, especially ones with loose chips, I'll often do a mag check in flight prior to landing. Care must be taken, but as it sometimes isn't advisable on a loose surface, doing checks in advance can be a benefit.
Take the time one needs; don't worry about how long it takes anyone else.