No. Runs must be performed continuously in one sitting. If you see a run you suspect to be cut (or "spliced"), you can report it to the game's moderators.

Your run has to include "player 1 wins" at the end of stage four. I'll approve it for now, but keep it in mind.

In the run rules, it is stated that the time starts when the first tip appears on screen. However, most runners, including myself and some moderators, start timing when clicking spacebar. This makes more sense, as it's the first button input of the run (and the first level is frequently re-rolled many times for better placements). I think the rules should be changed to start runs either when the space bar is pressed to dismiss the first tip (which is how most runs are already), or when the runner gains control of the player character.