In terms of distance, yes. In practice, mostly yes.
The isle of Jura, whilst only being just a little northwest of Glasgow, is a pain the backside to get to. The isle of Islay (Bowmore, Bruichladdich and other Distillerys) isn't as bad. Glen Ord is about a half hours drive north from where I come from, Dalwinnie about a half hours drive south. Cragganmore is probably a little less than an hours drive, Tomintoul about an hour.
I come from a small village called Tomatin. My old man works in the Tomatin distillery.
which is just one of many Speyside distillerys (the greatest concentration of distillerys in Scotland is to be found along the river Spey). Overall, it probably isn't far from the truth to say that I could get to almost all distillerys within four hours drive.