We have had refunds for five flights of nine, three from Jet2 and two from easyjet. Each refund came within six weeks of formal application against a stated aim of around four weeks. We never made any follow-up/complaint over the longer time taken - we took the attitude that they were probably quite busy.
On the other hand we have yet to receive refunds for two cancelled flights with Wizz, some eight weeks after application for a refund. Finally, we are still waiting for a refund of two flights with Ryanair more than three and a half months after being promised that they will refund. In both these cases we have converted the matter into a claim against the credit card used to buy the tickets, still waiting some 4-5 weeks after submitting those. In the meantime Ryanair very recently told me I have a voucher ! In fact, I have two separate promises from Ryanair that they will refund and the evidence is with the credit card issuer. On one card dispute (regarding Ryanair) I am promised resolution within six weeks from now, the other card (regarding Wizz) says it can't give me a time frame.
I suggest that if you eventually become impatient you have the option of lodging a claim with the issuer of the card you used to pay for the booking(s), assuming you paid by card. As you can see, it will still take some time after that, although my assumption is that the company is for much of the time unaware and if they refund in the meantime the card claim will automatically be closed, but you can also do that yourself for good measure.