Attitudes to bid size and loan part size

Apart from the very short term "secured" Property Loans I only ever bid in £20 chunks and rarely more than £40 or £60 in total.
Having been "burnt" by initially using the FC grading system I now review the financials and other info. on each bid and end up rejecting about 45%. Time will tell whether or not my new strategy works. The returns can look tempting if one can avoid the bad debts. I do not try "flipping".

I have found that when an attractive part comes up for sale, there is no time to review the info - the part is snapped up within seconds. So does this mean that you don't use the secondary market?

Does the speed with which attractive parts are bought mean that buy-bots are out there? I assume that a buy-bot would buy without looking at the info (tho' would use a blacklist) and then the trader would dump at leisure.

Depends on total amount you have invested. I prefer £100s and there is enough people out there that are happy to buy that. I have to say I sometimes dont buy the attractive £20 lots in secondary market as it would take too long given the awful site (you can click many of them at a time to buy, but only one part will be bought - the rest are incorrectly claimed as already sold (but if you click only one part, it will be bought OK)

I used to buy £100 parts, not really for flipping but for liquidity - not wishing to hold to term. They always sold fine through most of 2013 and I moved to a plan of buying C- loans at 11.5% in £100 parts and selling before the fourth payment. This got sticky in late 2013 and I moved to £40 parts which do sell a bit easier. I now buy £40 parts but rarely touch C-. Except for the property loans Where I buy in £100 parts and do not mind if I hold for the full 12-15 months. But £100 parts in 6313 have been selling well.

That is not quite right IIRC. Autobid always buys the largest part it can subject to the percentage of total funds set. Assuming that it is set to 1%, if the FC total is under £4000 then Autobid will only buy £20 loan parts. If the FC total is £4000 or over than Autobid will first look for a £40 loan part. This is because Autobid will buy only one part from each loan and the higher value parts lend out the money more quickly.
(My example is approximate of course because £20 can cost more than £20 with interest and £40 loan parts can cost less after repayments).
Of course £100 loan parts will only be bought by Autobidders with an FC total of £10,000 or more - which does limit the scope.
I do wonder what happens if you use Autobid with £1000 in a new account - presumably it will buy £20 loan parts at auction even though they are 2% of total funds.

Depends on how long ago that was - autobid used to have a much higher default percentage IIRC .. 2%, or maybe even 5%? However I am sure it's smart enough to know £20 is the minimum,  so it'll have to bid that even if there is only £20 in the account, instantly making you a diversity criminal.