I've always been told that all homework tells you more about the parents than it does about the children. I've also read in various places that spelling tests do little to help children learn to spell. children consistently get words right in their spelling tests and then immediately spell them wrongly in their independent writing - it's a recognised part of the process of learning to spell.
However, most schools do them because they are popular with parents, believe it or not. If a school didn't send home spellings to learn, they would have parents hammering the door to ask why not. Whether those parents then spend sufficient time helping their child to learn the words is another debate..
Anyway, I'm a big believer that once a child has learnt something wrong it is ten times harder for them to unlearn it and then learn it correctly. In the long run, it's far easier for a child to start to learn the high frequency words they use regularly but don't follow the phonic patterns they've learnt at that stage (for example, some, come, said), rather than continually sounding it out for themselves and getting the wrong pattern ingrained in their heads.
So after half term, my year 1s who are on phase 5 phonics will start to have a few spellings each week of common high frequency words and some which reflect what we are learning in phonics. If they aren't on phase 5, I don't feel they are ready to start learning words which don't follow the phonics they are learning so I'll support them in other ways to become confident in using the phonic patterns they know. But I've stressed to all the parents (those who came to my meeting anyway) that as far as I'm concerned, at this stage of year 1 homework is more or less optional - the children work hard in school all day and they will be tired when they get home. As long as they hear them read regularly, everything else is less important, in my opinion. However, if parents want to do more with their children, then the homework is there.