I've been working, on and off, on a universe with limited FTL based on the "one big lie" principle of sci-fi writing; travel speed averages just a hair over 4 times the speed of light, travel is instantaneous for the ships and crews travelling faster than light. Some time travel is demonstrably possible, ships do occasionally arrive before they leave, but because decisional causality can't be violated you can't do anything interesting with it. But most importantly, to this question, jump times, as measured from a non-FTL reference frame, can be rather variable (Poisson-ish distribution around the expected average with roughly 90% of the ships arriving within plus or minus 10% of their expected transit time on "standard" jumps) some ships will arrive as soon as, or even before, they leave, but never before the decision was made to send them, while others may take several times longer than expected to arrive.
A touch of background to the conflict; Humanity have been very worried about their weird alien neighbours for some centuries because they think that they could be squashed flat at a moments notice, as such they've sunk enormous resources into a huge battlefleet, all of six fleet carrier class ships, each one capable of pacifying any one system. Their neighbours for their part have concerns of their own, not being able to squash the humans and Humanity having advanced technology in areas that makes the aliens very vulnerable to certain routes of attack. The two are at peace, sort of; the aliens don't let us anywhere near certain installations and otherwise almost ignore us. They have no specialised warships but do have vessels that can be used in the role in an emergency that has never come. Oh and a few millennia ago they fought another alien group, their own overlord caste, to extinction and/or exile.
Technical details: No-one has FTL communications except by courier all intel gathering and ships comms are strictly lightspeed minus processing. So all intelligence gathered will be light speed lagged by the time you get it. In-system big ships are slower than small ones but when it comes to FTL bigger is better for several reasons, not least of all being heat dissipation capability compared to the size of the powerplant for the jump drive. Most populations are planetary but most material extraction and manufacturing is done off-world.
The current conflict; now the masters are back and our alien neighbours have asked for our help, between us we control a loose cone-like area that at their far frontier is a hundred or so light years across, no-one's sure, there's a small zone that unknowingly overlaps the "masters" self-exile. At a minimum they'd like to create a buffer in that area but ideally they'd like to wipe these guys out for good. The combined fleet is over a dozen fleet carriers, huge FTL capable vessels that are, in the case of the humans, heavily armed and carry large numbers of interplanetary warships, most of which are usually FTL capable in their own right, as cargo.
The question proper: Given a narrow interstellar battlefront of say 30 Light Years only a few light years deep say 10-15 systems in all and assuming a single strike unit can reliably pacify a given star system, but not a reaction force if one shows up, within days, is the fact that the strike forces' arrivals in the different systems could spread across up to 10 years or so going to hurt their ability to win the war or does a strike dispersion that small make no difference at such a scale?