How much “proprietary deal flow” in the UK LLM is actually proprietary?

For anyone on the deal side at smaller UK funds (sub £500m) - every fund deck and website goes on about relationship-driven origination and proprietary sourcing. But it seems like most deals in the £10-100m range still end up with an advisor running some kind of process anyway. Even if you met the founder first, any sensible owner is going to hire corp fin before signing anything.
So what does it actually look like day to day? Is "proprietary" mostly just code for "we had a head start before the auction kicked off"? I'd guess a lot of the genuinely off-market stuff is really just bolt-ons where the platform CEO knows the other owner.
Also curious if the rubbish exit market the last couple years has pushed funds to do more direct founder outreach or if advisor relationships still bring in most of the flow.
Not after anyone's secret sauce, just interested in the gap between what the marketing says and how it actually works.