Ask five different trainers how many days a week you should train and you'll often get five different numbers. The more useful question isn't "what's optimal" — it's "what will I actually keep doing." A near-perfect six-day plan you abandon in week three produces less progress than a modest three-day plan you're still running in month four. Consistency beats intensity almost every time, because training only works when it's repeated.
What two, three and four days each buy you
Two sessions a week is enough to build and maintain real strength and fitness, provided each session covers the whole body — it's a genuinely solid floor, not a compromise. Three sessions is where most sustainable progress happens for most people: enough frequency to practise movements often enough to improve at them, with a rest day between most sessions. Four sessions starts to allow real specialisation — splitting upper and lower body, or strength and conditioning, into separate days — but it also demands more recovery, more sleep, and more consistent eating to actually pay off. More days is not automatically better; it's only better if you can sustain the life around it.
Why rest is part of the program, not a gap in it
Training doesn't make you stronger. Training creates the stimulus; recovery is where the adaptation actually happens. Skip the rest and you're accumulating fatigue without the improvement that's supposed to come with it — which is how people end up training hard for months with surprisingly little to show for it. A rest day isn't wasted time. It's the second half of the exercise.
The mistake of starting at six days
The most common way a new routine dies is starting too big. Six days a week sounds committed, and for the first eight or nine days it usually is — right up until life produces one unavoidable clash, and the all-or-nothing plan has no room for a missed day without feeling like a failure. A three-day plan that survives a missed Tuesday is worth more than a six-day plan that collapses after one. Start with the number of days you can defend on a bad week, not a good one. You can always add a day once the habit is boring — which, for training, is exactly the goal.