You are incorrect. What you could do is accept all X clients, then extend their training duration by 999 weeks or some such.
Or you could use pretty much any of the cheat mods, since most of them offer auto training duration extension.
		
		
	 
Limited to 3/4 clients that you can interact with each week (up to five it there isn't any extra day-ending event during that week, and you prefer to train on friday rather than doing a weekend). I'd say in most cases, especially early game where story events happen frequently, it's very hard to train more than 3 simultaneously.
I understand you meant they can all be active clients even if not trained every week, my reasoning is the usefulness of having more than one client at a time comes mostly from being paid more each week. But the truth is you can also do work outside training, so from a strict cash flow perspective, I've been lately been adopting the slow approach of taking up one client at a time, at least until I've exhausted their weekend options, then perhaps a second simultaneously.
I do use your cheats, but even extending time, I'm finding it very grindy to earn enough for all the upgrades and presents that can help you, and the special items are extremely hard to come by, effectively meaning you always get less that you could use, tempting me to use your mod to spawn them (haven't done it yet). I find it more enjoyable when I can do as much as possible in a single playthrough vs. replaying with different choices, but that's just me.