I always advocate a "weeding" system rather than this idea of just chucking everything away after an arbitrary date.
For some documents, it wise to keep them (or a scan) almost forever - and certainly longer than 6/7 years. In this category, I'd put the likes of purchase invoices for assets (i.e. vehicles, equipment, etc) which often last longer than six years - for me, I'd regard the 6/7 years requirement as starting from the date the equipment or vehicle was sold or scrapped, rather than date of purchase. Same applies for paperwork concerning the purchase of property or a business. Also any long term contracts with customers or suppliers, i.e. the kind of contract that you sign once to cover the lifetime!
At the other end of the scale, I wouldn't lose sleep over minor expense paperwork being disposed of earlier than 6/7 years, i.e. petty cash, fuel receipts, stationery, etc. My criteria would be individual receipts of very low value, i.e. under £25 or where the record of the purchase is shown elsewhere, i.e. on a bank statement or credit card statement if paid by card.
For "normal" trade invoices, i.e. invoices to customers and from suppliers, then yes, the 6/7 year should be adhered to.
As for credit card and bank statements, both business and personal, I'd really try to keep them as long as possible - maybe more to around the 10 year mark.
I say all the above from 29 years of experience. Generally, as time passes, tax inspectors only look at the big things. Even if you're being investigated and they start looking at earlier years, they're unlikely to ask for your fuel receipts from 5 years ago. But, I do know of instances (one personally) where having proof of purchase from years ago results in free replacement or repair - i.e. where some equipment has been proved to have a safety or design flaw. It's not always for tax reasons that you may need the original paperwork.
So, I'd just weed it out, say once a year, with the aim of having a single file (or small box) to keep long term for each year. Each year, throw a little bit more away from every year. Of course, you could set up your current filing system into categories so that you don't have to go through it again - i.e. one box to chuck in 7 years, another box to chuck after say 4/5 and another to keep permanently.
But as said above, maybe better to start scanning stuff now so that you can safely shred it today and at least your piles of archives won't get any bigger.