Far from it. I'd break our transfers down into roughly 3 periods - 2001-2011 (ish), 2011-2016, and 2016-present.
That first period, our transfer logic was absolutely scattergun, though the rough common thread was trying to buy undervalued young talent. The market dynamics worked in our favour, and combined with early attempts at data-driven scouting (with Comolli), we picked up the occasional gem that, when it came together, formed the core of that Redknapp side - Modric, Bale et al.
That middle period, from 2011 to 2016, was almost a golden era in the sense of the majority of our signings being hits. Data-driven scouting and player identification reached its apex, with Michael Edwards (and then, Paul Mitchell) leading the acquisition of a core of genuine, undervalued talent, from Walker (2011) to Lloris, Dembele and Verts (2012) to Alderweireld, Son and Alli (2015). Kane's emergence set the seal on it, but there was a strategy at play that meant more players were hits, than misses. Even bit-part players like Davies, Trippier, Wimmer et al were dependable and became pillars of the team later on. Yes there were interludes like Franco Baldini in between, but it was an era where we seemed to have a plan.
2016 and on was when both the above transfer experts (Edwards and Mitchell) left, and we brought in the execrable Steve 'I hate January' Hitchen and his ilk to run scouting. We can trace our downfall to that moment, as well as the decisions to pass on the likes of Sadio Mane and Georginio Wijnaldum for N'Koudou and Sissoko.
From that point on, with the diktat of 'cheap wages' always an iron law at Spurs, we went on a spree of signing often bad players that no one else wanted, for very good reasons. Unable to shop in the top tier, and increasingly locked out of the truly talented youngsters (because by then everyone was looking for the next Bale and Modric, and had the money to outbid us), we stocked up on average players who ended up doing us in.