In 1996, I got a job on the Oxford Science Park at the South of the city. My girlfriend had just moved to Stratford upon Avon, so I tried commuting from there by train and Brompton. I could get trains that would get me to work at 8am or 10am. I lasted a fortnight and bought a car. After a year, I bought a house in Abingdon which was a couple of miles from Radley station at one and and work was a couple of miles from Oxford station at the other end. Cycling was just as quick. Buses were OK, but had a load of speed bumps.
After a couple of years, I got relocated to Cambridge, and bought a house in Ely. Commuting by train would have been possible for a couple of years. Then my employer moved to Granta Park, where the selling point was it was close enough to Cambridge to have a CB1 post code, an 01223 telephone number, and was far from Cambridge itself. Commuting by public transport would have taken just under 2 hours each way by public transport, or 30-40 minutes by car. After a few years, I changed job to the North of Cambridge, at the midpoint between Waterbeach and Cambridge stations. Commuting by train was possible with a Brompton, but not really with a full size bike. I had a year where I walked to and from the stations, which was good for my waistline, but meant walking for 80 minutes each way on top of 20 minutes for the train. When Cambridge North opened, that came down to 45 minutes to walk each way, so it was still slower than driving, but nicer. Then Covid happened, and now I can work from home 98% of the time, which is a much nicer commute.
Commuting from Ely into Cambridge is a realistic proposition to a number of the main employment areas, where you have a choice of 8 car electric trains, or Greater Anglia ones where the off peak tickets are quite a bit cheaper. When I moved to Cambridge in the late 90s, the service to Newmarket was really poor. The frequency has improved, but not enough to attract me to rely on it. House prices near the railway to the South of Cambridge are quite a bit higher than to the North and East.
If I was moving to work in Cambridge now in my 30s, then I would be priced out of Ely, and would need to be looking in Littleport and Downham Market. When things work well, that doesn't take that much more time, but there is much more chance of long delays when the trains are delayed.
The train services have improved around Oxford since I tried using them in the 90s, but not by much, and certainly not from Stratford upon Avon, where you would now need to change trains to get to Oxford.