as a team I'd say 5-6 games but as a player 3-4 games.
If a player has 3 or 4 bad games they've lost form for certain. As a team you can excuse 3 or 4 games as it could be pinned on individual mistakes but any more than 5 or 6 then form is out of the window.
Funnily enough I was just looking at the last 4 league results for us and Rotherham and we took 10 points from 12 and they got 5 from 12. We timed our winning run to perfection.
Could depend on the timespan of those games and being a settled side. I'd say fitness as in not fatigued but also match fitness, confidence and momentum, as well as being injury and suspension free all being part of what you'd expect to judge equally, if trying to predict anything based on form.
Usually stats are as you read them. A team who has only won eg 2 in 12 coukd be tge same team who has only lost 1 in 8 or unbeaten in 5 at home or some other misleading stat. Sequences need to be viewed over the longer term therefore imo and not necessarily form related.
City were a goid example as until we beat Wycombe had not won away all season but high in the league barely lost any games etc.