This seems odd in our modern times, but many "experts" think that it was much more common in the past. Maybe that was because there was only one peerson in the house that could read, or there just weren't enough books for everyone to have one. There's a lot of sense in it for other reasons too.. Especially when you're reading in a second language. Apart from anything else, you really really really need the practice...I don't think it occurs to people that one of the reasons they find it difficult to "use" their Welsh, or French or whatever....is the simple fact that they are not used to making those words, actually producing them vocally.
Certainly, in my French lessons at school rather a long time ago, we hardly ever spoke any French at all ...maybe the odd word when our so-called "teacher" asked us for the word for " carrot" or something. . It was all writing, reading, testing, basically keeping us quiet. I'm glad to say that things have moved on since then. Mostly.
As you may know, there are such things as "immersion" courses, where most of the time ( all of the time) the students listen to and speak the target language. They learn in much the same way as tiny children do ... by listening, copying, speaking and correcting as they go along. There's Welsh versions of that going on all the time ... notably the "wlpan" courses.
Obviously we can't all do things that way, but taking every opportunity to speak the language out loud should be pounced on. Also, don't forget my magic bit of advice ... remember that you can talk Welsh for as long as you like, wherever you like as long as you are talking into your mobile phone. It doesn't even have to be switched on. It's brilliant ! You can do it walking down the street, in the shops, at work, on the bus ...
Yep, it works. And one more thing ... you know what it's going to be ... one of the very very best ways to vocalise Welsh pleasurably, naturally and beautifully is to sing Welsh songs. Anything will do, from Nursery Rhymes to 9bach, from Datblygu to Diffiniad, from Hwiangerddi to Hanner Pei to Huw M, and from Gorky's Zygotic Mynci to Gwyneth Glyn .... Ha! bit of a coincidence there ... here she is .. complete with words and everything, so you've got no excuse..